sloth and torpor
The hindrance of sloth and torpor consists of two aspects: physical sloth (thina) and mental torpor (middha).  Its antidotes are a range of methods, from the subtle to the gross, of getting yourself to WAKE UP!
For mental torpor, which is a dull, sleepy, stiff, rigid state of consciousness, you can first of all try to counteract it by stimulating energy.  You could reflect on the inspiring quality of sympathetic joy, for example.  Or if need be you can interrupt your current practice and start actually practising Metta and Mudita Bhavana.  Or you could try to make your experience of the object more vivid and energizing: if you are visualizing a form, for example, you could imagine it as shining and vibrating with light and colour.  If you are concentrating on a sensation such as the breath, you could pay attention to its more stimulating aspects, for example, finding the place in the body where the sensation is strongest.
For physical sloth - which may range from a slight lack of vitality, through head-nodding, to complete collapse and sleep - strong medicine is often required.  You will have to make a very strong resolution not to give in to drowsiness, because it could take all your energy just to keep awake.  The very nature of sloth is to avoid working in meditation; the desire to do absolutely nothing is remarkably strong.
For this reason it is vital to recognize this hindrance right from the beginning.  Recognition can be a major step, even a breakthrough! Even though you recognize sloth and make efforts to work against it, sloth will still persist in `hiding' from your awareness.
Even when you begin to get it under control, you need to keep checking to see whether sloth is still there.
It may help if you have your eyes open, at least enough to let in sufficient light to stimulate you.
You could also have as much light around you as possible - at night, for example, you could have all the lights switched on.  What is more, you should not hesitate to break your meditation to get up to switch them on, provided your action will not disturb others meditating with you.  Getting up will not harm your meditation - under the power of this hindrance you were not meditating anyway.  On the contrary, by opening your eyes and switching on the lights you are doing something to enhance your practice.
If staying awake gets very difficult, you could try gazing at a source of light, for example a candle; or, if it is daytime, try gazing into the sky (not, of course, directly at the sun) and meditating.
You could open a window: you could get up, interrupting the meditation, and open a window, and breathe fresh, cool air.  Perhaps you could wear less clothing, too - if it keeps you awake, it is better to be a little cool rather than let sloth get the better of you (though for some people coldness encourages sloth - so they might need to warm themselves up).
It may also help if you concentrate on the breath high in the body, for example at the nose or imagined at the top of the head - this can work very well.  Indeed, paying attention to your body can be a very effective method indeed.
If the sloth is very strong, you may be able to prevent yourself from completely `going under' if you concentrate entirely on your posture.
The tendency with this hindrance generally is to sit very slackly, with very little bodily awareness; in particular there is a tendency to lean too far forwards, with the head bowed and nodding.  A good physical antidote is to lean slightly backwards, and to tilt the head back a little.
If you are definitely sleepy, you can stop meditating for a while and stimulate yourself physically.  You can rub and massage your limbs, change your posture, pull your earlobes (a traditional recommendation), or pinch yourself!
Something of this kind may revive you - but if it does not, it is best to give up for the time being, have a break, and sit again later.  You could take a short break, perhaps washing your face in cold water before returning almost immediately, or walking mindfully up and down outside for half an hour or so.
In the last resort, you will have to conclude that you need sleep! So then you should lie down and sleep, continuing the meditation later when you are refreshed. 
Or you can try to remain aware as you fall asleep in the meditation.  Allow yourself to drop below the threshold of consciousness, yet remain curious about the state of mind (which after all is deeply mysterious) – try to experience what is happening as you dip down and come back up again.  In this way you don’t really break off from the practice.
Taking another approach, sloth can often be transcended if you chant or recite out loud, which is both physically and emotionally stimulating.  For example, you can chant traditional verses, of which there are some very beautiful ones in the Buddhist tradition.
There are also a number of visualization techniques traditionally recommended for dissolving sloth and torpor.  You can, for example, visualize light - brilliant white light - inside your body and head, and then imagine it glowing and radiating outwards from your body.  Tibetan teachers sometimes recommend visualizing a point of white light inside your heart which shoots upwards out of the crown of your head, merging with the sky.
But finally, if the standard antidotes do not seem to be working, you can try calming down and relaxing! Sometimes sloth and torpor is caused by underlying tension: you may not be allowing yourself to experience some emotion, so that the effort of repressing it is absorbing all your energy.  If this is the case you should try to relax and experience whatever emotion is there, releasing the tension and bringing back your energy.
The hindrance of sloth and torpor is not a very suitable basis for Dharmic reflection.  Theoretically it is possible to contemplate the impermanence, unsatisfactoriness, and insubstantiality of sloth and torpor just like the other hindrances, but it cannot be generally recommended.  Anyone who wishes may try reflecting in this way if they like - if they can!
Sloth and torpor probably requires a much more down-to-earth course of action.  You are half asleep, stuck in dullness - so you need to wake up; you really need to give yourself some kind of positive shock.  Traditional Buddhism can provide a number of suitable reflections.
You can reflect, for example, on the shortness of your life, and on how precious the opportunity of life is.  Readers of this book have probably been born into a very favourable situation.  Not only are you alive and in a position to develop yourself spiritually, but you even have some idea how important spiritual development is.  How few people have this - how few are in a position even to think about it! Most people have little time to think of anything but supplying their immediate wants and needs.  But you are able to function more fully as a human being; in our present world that is a privilege, not a right.
What is more, you have actually come into contact with the spiritual path, something that most human beings are unlikely to do.  Moreover, you could hardly be in a better position to put its teachings into practice.  You may, perhaps, be relatively healthy, and with the political freedom to practise as you wish.  For most readers, Buddhist literature and Buddhist teachers will be widely available.  If you do not practise the Dharma now, when else will you have such an ideal opportunity, when else will you be able to make any progress?
Traditional Buddhism would point out that if you neglect these opportunities, you are likely to forget that they exist, and become even more immersed in the endless round of cyclic existence - you are unlikely to come across something like this again for many lifetimes, and, even then, are you any more likely to take advantage of it, since at this moment you are responding lazily to an insignificant difficulty like this hindrance?
You may not accept the traditional Buddhist idea of rebirth, but these arguments do not really depend on the idea of future lives in any case.  There would be no point putting things off to some future life, even if it did exist, because if you don't make an effort now, when will you? There really is no excuse for laziness once you have accepted the need to develop yourself.
Another approach to the `positive shock' is to consider the inspiring qualities of others, in particular their heroic qualities of energy.  The Buddha, for example, was a wonderful example of energetic dedication to his work.  From his youth he worked on himself, until at the age of thirty-five (some say twenty-nine) he gained Enlightenment.  After that he simply gave himself for the benefit of others, travelling and teaching constantly, often in very trying circumstances, right up until his death at the age of eighty.  Even on his deathbed he gave an ordination, and immediately before his death the few last words he uttered, in front of a great crowd of disciples, summed up his entire teaching.  He said, `Monks, all conditioned things are impermanent.  With mindfulness, strive on.' Together with the cultivation of awareness, he clearly regarded the putting forth of effort as absolutely vital for human progress.
sky-like mind
Some people might possibly be able to use this method for sloth and torpor, but since the most likely outcome is simply an increase in the hindrance it cannot be generally recommended.
Sloth and torpor is generally a `passive' hindrance; there isn't really anything there to be suppressed.  Suppression is brought about by actively cultivating an antidote.
outside meditation
If you are habitually slothful or torpid, there are bound to be factors at work in your life which are encouraging it.  You could look at the traditional classification of body, speech, and mind: as far as your physical body is concerned you need to get enough but not too much exercise, so you are neither sluggish nor constantly tired.
You should be aware of how much you eat; again, the ideal is not too little, not too much.  The type of food can also be important; it is a good idea to avoid too much stodgy, fatty food.
You also need to get sufficient - though not too much - sleep.  Too much will make you dull and dreamy, but too little will have a similar effect; either extreme can cause sloth.
Regarding speech, it may help if you try to avoid being passive and dull in speech.  You could have a policy of always saying what you think, and of not being afraid to speak out.  Perhaps you could also try to speak more energetically, and only get involved in lively conversations! Avoid speaking dully and pessimistically.
Mentally, you might be able to alter the tendency towards torpor if you cultivate the friendship of energetic, active, lively people, and motivate yourself through Dharma study.
doubt and indecision
First of all - as always - one must acknowledge that this is indeed the hindrance of doubt (vicikiccha).  In the case of this hindrance, it is the implications of recognition that are important, because as soon as you have recognized that the hindrance of doubt and indecision is present, that it is a hindrance, and that you do not want it - you must decide, firmly, that you are going to do something to change things.
You can recognize doubt and indecision by the fact that you are holding back; you are not really putting yourself into the practice.  It is as though you do not trust the meditation - which probably means that you lack confidence in your own potential.  Possibly, you are a little afraid of your own power.  But anyway, whether this is the case or not, you certainly lack trust in either the practice or your ability to engage in it.  This lack of trust causes you to hold back from committing yourself to a line of action; and your not engaging has the effect of laying you open to the other hindrances.  You can sometimes see this ability of doubt to `underlie' other negative states when you successfully ward off a hindrance such as restlessness, only to discover doubt lurking underneath.
Since this hindrance is essentially a lack of resolve, to develop a positive sense of resolve is an important counteragent.  You might be able to develop this by impressing upon yourself the seriousness of what is happening to you.  Doubt and indecision is certainly a very serious obstacle to your progress: its nature is to maintain a chronic state of unresolvedness, in which you actively resist the idea of clarifying your attitude.  You continually allow yourself to avoid facing up to and clarifying important issues.  This is why most of the methods recommended are either of the consideration type or are to be employed outside meditation.
The hindrance of doubt and indecision could be worked on with the more `vipassana'-like considerations of its impermanence, nonselfhood, and unsatisfactoriness, which have been applied to some of the other hindrances.  These can certainly be experimented with, but in practice it seems more useful to work more `psychologically'.  Your basic need is to develop confident resolve, so you can consider ways of clarifying the unconscious confusions which sap your confidence.
You could try to discover, through conscious reflection, whether anything is not clear to you - perhaps something to do with the practice you are doing, or something about Buddhism, or the path of development generally.
Having isolated a specific doubt, you can then put it aside, deciding to think it through later.  But if it seems there is no chance of getting into the meditation otherwise, you might as well think it through now.
You could try to develop, through conscious reflection, a sense of confidence in yourself.  You need to believe that you are justified in having confidence in yourself.  Many people find this almost impossible, so to overcome this obstacle you must assess yourself quite objectively - that is, not negatively (`obviously I'll never be able to meditate'), nor over-optimistically (`I really am wonderful')both are clearly unreal.  In Buddhism it is considered a great virtue to rejoice in objective merits and good qualities - including your own.  You might well need others to verify your self-assessment in order to believe it yourself; you can then encourage yourself much more.
You can reflect that through practising meditation you develop yourself, and that there is no limit to the extent you can develop.  Buddhist teachers say that you can never be sure of the results of any worldly undertaking - but spiritual practice inevitably has good results! The sincere will to develop always produces fruit, because that is the way of human development: intention is everything.  If you have been meditating for a while you can ask yourself - and your friends - whether you have actually made any progress.  You will inevitably find some improvements in your life, however small.
You can ask yourself whether it is objectively possible to grow and develop.  The answer has to be `yes'.  Then you can ask, well - do you yourself want to develop? If again the answer is `yes', then the obvious thing to do is decide to make a little effort towards it! As soon as you accept that you want to grow (emotionally accept it and its implications, not merely acknowledge the idea), then you have begun to clarify your confusion and are in a position to make a decisive effort.  Then, if doubt rises up again (as it probably will), you can again work through these reflections.  But if the answer to either of the questions above is `no', you have not thought it through clearly!
Or perhaps you are stuck in the present moment; perhaps right now you are not in the mood.  But even that really evades the issue, for in the long term, if you understand what personal development is, you surely want it.  Or perhaps that is the problem; you don't know what it means to `grow and develop'.  But that is a manifestation of doubt too! You need to work at it again and again until you see more clearly.  It will obviously help to talk with friends (the more positive ones, rather than the cynics) about the issues it raises.
sky-like mind
This can be a useful way of experiencing your doubt and indecision, once you have recognized it.  It can be useful to `size up' its character by allowing it some space.
This is similar to sloth and torpor in that there is nothing to suppress - except your resistance to doing something.  So to suppress doubt and indecision, be decisive!
outside meditation
Generally, you need to understand your doubt and indecision more deeply; you need to become more aware of its nature and its effect on your life.
All its manifestations are merely the products of a mental state, not rational thoughts - it is not that you genuinely do not understand something, not that there is a definite reason you are unsure.  The hindrance of doubt and indecision is an emotional state which always looks for reasons to doubt things.  If you look more rationally at the doubts themselves, you may be able to see the deep irrationality of this most poisonous hindrance.
In doing this it is necessary to generate a special mindfulness of the way that you think and use ideas.  It is especially interesting to observe how you receive new ideas.  In what ways do you accept or reject them? When they seem true to you, do you really accept them, or are there further reservations? And if there are, do you examine what the reservations are, and voice them to others?
Keeping ideas to yourself, to avoid the risk of having them challenged, is a typical ploy of this hindrance.  So as a counteragent, you can make a practice of speaking out when ideas do not seem right to you.  Even if at the time you cannot articulate your objection precisely, a lot may be gained by mentioning that you are not sure about something, or that you feel that something might be wrong.  When you practise thinking more critically like this, you should not be closed-minded either, but open to discussion.
Through this practice you learn to monitor your thinking and to notice the emotions which lie behind your thoughts.  It is the uncomfortable emotions which cause you to hold back from decision-making, so having realized this you can try to unify your thinking and your feeling, both by bringing more clear thought into your actions generally and by trying to have more emotion in support of your decisions.
Another approach you could take is simply to be more decisive outside meditation - you can do this by being more aware of your indecisiveness, recognizing symptoms like wavering, dithering, and lack of clarity.
It will also help combat this hindrance if you form associations and friendships with people who are helpful and encouraging.  You should recognize that you need support - you need friendship and the confidence that friendship gives.  A lot might be said about how to acquire friends, but the most effective method is simply to be one.
You can also try to make a connection with an experienced spiritual teacher.  This need not be some famous `guru'; all you need is as frequent contact as possible with somebody a little more developed and experienced than yourself.
It will also increase your confidence in yourself generally if you think less about yourself - and, instead, affirm and give your support to others.  You can let them know how much you appreciate them, praising them for their virtues, and surprising them with your expressions of esteem! `Rejoicing in merits' can be astonishingly powerful.  Many people never seem to receive any appreciative comments about themselves from anybody.
It will definitely help your clarity of thought to develop a better intellectual understanding of the principles of Buddhism.  You need to be quite sure that your understanding is correct, so that you can trust and use it.  This can be achieved particularly through discussion and by formulating questions.
Finally, you can view the need to overcome doubt in terms of developing trust or faith in the spiritual path.  Faith in Buddhism is never `blind' faith; it is always based on a modicum, at least, of experience.  So faith is developed through reflection - but once that has been awakened, even to a tiny extent, it can also be greatly strengthened if you perform devotional practices such as pujas and chanting, in which you not only celebrate your understanding of the Dharma, but try to contact the potential for Enlightenment within yourself directly.  Devotional ceremonies exercise your more artistic, playful, imaginative energies.  As an antidote to your chronic doubt and indecision, you could perhaps be really lavish with them, with special shrines, offerings, or whatever else appeals to your imagination.