moving `up' to a better posture
It is  important to remember that there is  no point in trying to force yourself into an ideal position that you  cannot sustain.  The correct posture is the one which enables  you   to be as relaxed and as alert as possible within  your  physical  limitations.  You need to be sensitive, not forcing your body but caring  for it, working as best you can with what you have.
However, in terms of the principles outlined earlier, some sitting  positions are definitely better for  concentration.   For example, the cross-legged full  lotus posture gives  the best skeletal balance.  On the whole, it allows more access to  subtle physical energies than other postures, and it is also (if you  are used to it) the most comfortable position for long periods of  sitting.  The next best is some other form of cross-legged posture,  for example the half lotus, or a variation of it (fig.3).  Then come,  in order of preference, kneeling on a  stool or  cushions,  and sitting on a  chair.  All these positions can be very good  for meditation, but though you can meditate effectively in any of  them, you should always aim for the position which affords the most  relaxation and alertness.
how exercise can help
Of course, the trouble with such advice is that our stiff  joints and weak muscles are not used to it; they are going to hold  us back.  Can anything be done?
Whatever your age and however stiff you are it is possible,  over time, to make some progress in loosening your joints and giving  your muscles more strength and tone by taking a little regular exercise.   There are many systems of exercise, and within each system there are  many exercises.  I have collated here a small selection which can be  used to work on the parts of the body most affected by meditation  practice.
be gentle with exercise
A warning is required before you read about or try these  exercises.  The problem with learning exercises from a book is that  without a teacher you may do them incorrectly and damage yourself.   If you do not fully understand how to work in a particular exercise,  you may become over-confident, push yourself a little too hard, and  overdo it.  At worst, you could put your back or knees askew, painfully  and even permanently.  So, while the exercises which follow can certainly  be experimented with, you must be very gentle with yourself.  If you  decide to take them up seriously, find someone who can help you to  do them correctly.
four types of exercise
Of all the many different types of exercise, four stand  out as being particularly valuable, though each is quite distinct  from the others.
Firstly, there is the approach of standard Western `PT' ( physical training), which usually involves the vigorous movement  of selected parts of the body.  There are many kinds of PT some  very specific, like weight-lifting, others more general.  With PT there  is less emphasis on bodily awareness, but some very effective methods  for stretching and strengthening particular muscles have been developed.   PT is good for keeping basically fit.
Then come two Eastern disciplines, t'ai  chi and  hatha yoga.  T'ai chi involves the whole body in a very fluid,  dance-like movement.  Practised consistently, t'ai chi develops physical  stamina and `grounded' body awareness, and combines this with awareness  of body movements.  Yoga seems at first sight more static since it  involves special postures (or  asanas  in Sanskrit) rather than  moving exercises, but within each posture there is a complex of inner  stretches, movements, and relaxations.  Yoga is perhaps the most exact  of the physical disciplines, combining training in bodily awareness  with specific, directed exercise.
Another kind of `exercise', the  Alexander Technique,  does not involve exercise, as such, at all.  Like t'ai chi and yoga,  it trains the student in awareness of the body and its movements.   But it is unique in that it does so in the context of ordinary, everyday  movement.  Practitioners learn how best to use their body how to  re-train the bad postural habits they have acquired over years.  I  have not included any Alexander Technique methods here (apart from  the relaxation at the end) but some people may find it well worth  looking into. 
These four types of exercise have been chosen to demonstrate some  of the basic approaches.  Obviously other methods are widely practised,  for example ` martial arts' such as karate or aikido.   From the exercise point of view, these combine different elements  of the four types.  Teachers of all four methods are widely available  these days.  You could consider either learning one, or a little of  each.  Perhaps the ideal approach would be to get a thorough grounding  in one physical discipline, and then learn a little of one or two  others.
For  strengthening and stretching   ankles, you can try the ` duck walk'.  Walk about  the room in curves, not straight lines on the outside edges  of your feet (fig.19), keeping the feet straight.  You can also try  lifting your toes and walking at the same time.
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Figure 19 – walking on the outside edges of the feet to open and strengthen the ankles
Knees  can be gently exercised by standing against  a wall and supporting one thigh at a right angle from the wall with  clasped hands.  Relax both the ankle and knee, and then swing the lower  leg (fig.20).  It is important to relax the hip on the supported side  and really `give' the leg to the supporting hands.
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Figure 20 – gentle exercise for the knees
You should rotate the lower leg only very gently and slowly, with  just a very little sideways movement swing mainly to and fro.   The knee joint has very little sideways flexibility, and stretching  it sideways too much, or too sharply, will damage it.  It may be easier  to do this exercise sitting on a table, dangling both lower legs (i.e.   knees, calves, ankles) and swinging them from the knee.
(1)  For  thighs, you can stand  on one leg near a wall (close enough so that you can reach out and  regain your balance if necessary), holding one ankle with the leg  bent back behind you (fig.21).
The hip on the supported side needs to be relaxed so that it drops  to the same level as the other hip.  The top of the pelvis should tilt  backwards with the tail-bone tucked under; the spine and chest should  gently lift.  Try to relax and release the thigh muscles as you stretch  the thigh.
Then repeat the exercise for the other leg.
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Figure 21 – exercise for thighs
(2)  Here is a  skiing exercise  which is good for thighs.  Stand at an arm's length, sideways, from  a wall, with your feet together.  With your hand on the wall for support,  keeping the feet flat on the floor, trunk upright, knees together,  and hips at right angles to the wall, lean towards the wall, bending  your knees and arm as you go down (fig.22).  Then repeat on the other  side.
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Figure 22 – skiiing exercise for thighs
hips and pelvis
The  hips and  pelvis are often stiff  and in need of opening up.  These exercises especially help improve   cross-legged positions.
(1)  You can try kneeling on all fours, with  knees wide apart and toes together.  Then with your buttocks kept low,  you take your chest and arms forward on the floor (fig.23).
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Figure 23 – opening up the hips and pelvis
(2)  Or kneel with one bent knee forwards,  the other leg bending straight back along the floor behind you, the  foot in line with your leg.  You support yourself with straight arms,  palms against the floor on either side of your trunk.  Then turn in  your waist towards your kneeling leg (fig.24).
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Figure 24 – stretching thighs and hips
(3)  Again, try sitting cross-legged on the  floor and cradle one leg in your arms, holding your knee and the sole  of your foot between your elbows.  Then swing the leg gently from side  to side or in a figure of eight.  This is good for knees and thighs  (fig.25).
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Figure 25 – opening the hip joints: gentle exercise for knees and thighs
knees and thighs
(1)  Lie on your back with your legs out  straight, gently bending one  knee and  bringing  it close to your body by clasping it with your hands.  At the same  time, keep your other straight knee on the ground (fig.26).
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Figure 26 – exercise for knees and thighs
(2)  Or squat down on the floor with your  feet apart, holding the knees inside your elbows and clasped hands  (fig.27).
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Figure 27 - exercise for knees and thighs
T'ai Chi
There are a number of very useful general exercise movements  in t'ai  chi which are good for loosening and relaxing as  well as strengthening the whole bodily framework.  Here is one.
Stand with your legs a little apart, feet facing forwards.  You should  not stand up straight and erect, but bend slightly at the knees, letting  the lower pelvis tuck forward.  Let the shoulders relax and the arms  hang loose.  Become aware of your breathing, at the same time becoming  particularly aware of the stomach area.
Then, keeping your feet where they are for the time being, rotate  your whole body from head to ankles gently from side to side,  letting your arms swing freely.  Let the arms lift out and swing away  from the body as the rhythm of the rotation gets under way.  Swing  round to the left, round to the right, turning the abdomen, chest,  neck, and head, all together in one fluid motion.  As your momentum  builds up, let the shoulders relax as the arms swing; let your loose  arms fall naturally against your trunk, if need be, each time you  turn.  You shouldn't turn violently, but gently and evenly.
Get more and more involved in the movement.  As you swing to the left,  let the weight of your body move onto your right foot.  As you swing  right, feel the weight on your left foot.  Keep the knees bent they  can be well bent now and the lower pelvis tucked under.  When you  are performing the movement easily you should feel that the momentum  comes only from your abdomen.
After a while, move your feet too; turn each foot on the heel when  your body turns, so that when you are three-quarters of the way to  the right the right foot comes round on its heel to follow the swing  of your body.  As you turn back to the front, turn your toes to the  front.  As you go round to the left, turn on the heel to the left in  the same way (figs.28, 29).
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Figure 28 & 29 – swinging from side to side, loosening and strengthening the whole framework of the body
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Figure 29
In spite of such a long description, this is a very simple, relaxing,  and enjoyable exercise! Give it time it may take five minutes  at least to get into the feeling of it.  This exercises and tones your  whole body.  It is especially good for the shoulders, hips, and abdomen.
hatha yoga
Yoga is  probably the most thorough of all  the physical disciplines.  There are hundreds of specific   asanas   for developing every part of the body, only a few of which can be  included here.  The emphasis in yoga is on being aware of, and deliberately  working, every part of the body in each pose.  Inner  relaxation  and subtle movement is consciously `directed' through close attention  to what is happening in the body, but (as in the Alexander Technique  training which follows) these subtleties can only be appreciated fully  through communication with a qualified teacher.
First, here are two simple  leg stretches which increase the  suppleness of the leg muscles, strengthen the  knees, and  loosen the  hip joints (figs.30, 31).  (These are not in fact  traditional yoga exercises but are often taught in yoga classes as  a `warm-up'):
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Figure 30 – developing flexibility in the knees and backs of thighs
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Figure 31 – sideways leg stretch
front leg stretch
Stand upright, with your feet together, in front of a  raised ledge that is a little below waist height (the height can be  adjusted according to how supple you are).  Draw in the muscles of  the thighs and knees so that the kneecaps lift up.  Then, raising one  leg, place one heel on the ledge, so that your leg reaches out in  front of you (keeping the knee straight).  The ledge should be at a  height that allows you to do this bearably, but with a good stretch.
Stand erect with both feet pointing forwards, arms relaxed at your  sides.  Concentrate on what is happening in your body, encouraging  your chest to open and your shoulders to relax back as in meditation  posture.  Continue to lift your leg muscles.
After a while, change legs.
This, and the next exercise, will develop the flexibility of your   knees and the backs of your  thighs.
sideways leg stretch
The sideways leg stretch is good for the  hips.   You use the same ledge as before or a lower one if it is difficult this  time standing sideways to it.
Lift one leg and place your heel on the ledge with both legs and your  knees straight as before.  Have your toes pointing upwards, and your  trunk in line with your standing leg, placing your hands on your hips.
triangle pose ( trikonasana )
Triangle pose  is performed in definite  stages, and each stage should be regarded as part of the pose, so  that your awareness is not scattered.
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Figure 32 – Triangle pose (1) – stand erect…
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Figure 33 – Triangle pose (2) – legs apart, feet to side…
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Figure 34 – Triangle pose (3) – extend over…
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Figure 35 – Triangle pose (4) – raise arm and look up
(1)  First stand upright with your feet together,  knees and thighs lifting, hands loose at your sides.  The coccyx or  tail-bone is slightly tucked under and forward.  Relax mentally, concentrating  and increasing awareness of the body.
(2)  Now take your feet about a metre apart,  feet facing forwards.  Then turn your right foot out ninety degrees  to the right, and point your left foot just a little to the right.   Raise both arms to shoulder height, keeping your head facing in front.   Next, leading with your right arm, extend the trunk sideways over  the right thigh, without bending your knee, and keeping your legs,  hips, waist, and shoulders all in a straight line.  Hold the calf as  low down as you can while keeping that straight line.  The head is  still facing forwards, neck relaxed, knees and thighs still lifting.
(3)  Next extend your left arm wrist,  hand, and fingers too upwards to the ceiling, and turn your head,  looking upwards.  Remain in the pose for a few breaths, trying all  the time to make it more steady.  (If you can keep your awareness in  your feet and legs it will be easier to do that, and the pose will  generally feel more satisfactory.)
(4)  Then, keeping your knees straight, come  up to the centre (on an inhalation, ideally generally, try to  be aware of your breathing) with arms outstretched and feet facing  the front.
Turn your feet to face the front, and do the same pose on the other  side.  Turn your left foot out to the left, your right foot slightly  in, and (on an exhalation) extend over to the left as before.  It can  help to do this with your back against a wall to keep your trunk and  legs in a straight line.
Triangle pose is an excellent all-round pose.  It develops  flexibility  and strength in your  legs,  knees,  hips, and  lower  back.  Take it slowly, and don't strain.  Do the pose  twice or three times on both sides.
cobbler's pose ( baddhakonasana )
Cobbler's  pose is good for loosening  at the  hips, and regular practice of this pose will make it  easier to sit  cross-legged.
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Figure 36 – cobbler’s pose: loosening the hips
Sit on the floor and bring your heels together near your body, catching  your feet with your hands.  Sit upright with an open chest (it might  be helpful to have your back against a wall).  Then concentrate on  the groin and thigh muscles and try to relax in the groins.  As you  do this your knees will move down towards the floor.
Two people can help one another in this pose if, as you sit against  a wall, your partner kneels so that their knees hold your heels close  to your body.  Then your partner gently places their hands upon your  knees without applying pressure.  Now you relax in your thighs and  groins; the weight of their arm will help stretch your thigh muscles  slightly and give you some tension to relax against.
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Figure 37 – a partner can help you relax in this exercise
It is beneficial  to lie down and relax,  maintaining awareness, after any session of exercise, and this is  especially recommended after  yoga practice.  The  Alexander Technique form of relaxation which follows (figs.38, 39) can be used.
alexander technique
There are no specific exercises in the Alexander Technique it  works through developing awareness of how we use the body in everyday  activities like sitting, standing, and walking.  But Alexander teachers  do recommend the following.
general relaxation
Sit down on the floor with a small pile of paperback  books say one or two inches high  two to three feet behind  you.  Bending your knees, allow your feet to rest flat on the ground  at the same width apart as your shoulders (fig.38).
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Figure 38 & 39 Alexander semi-supine position
(1) – sitting down for the relaxation…   (2) – final position
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Figure 39
Now roll your back down on to the floor, supporting yourself with  your elbows and lower arms, until you are lying on the ground with  the back of your head resting on the books.  Using your hands, adjust  the position of the books if necessary, so that the bony back of your  head is resting on the books without their touching your neck.
You may need to adjust the height of the pile so that your head is  neither dropping back and down towards the floor, nor raised up to  the point where your chin presses down on your throat, causing discomfort.   Have the pile too high rather then too low.  Generally, your forehead  should be slightly higher than your chin.
Then bring your feet a little closer to your buttocks, so that your  knees balance easily as they point towards the ceiling.  You may need  to take your feet a little further apart or closer together to achieve  this balance.  A certain amount of muscle tension may be necessary  to maintain this position, but it should be as little as possible  so that there is no gripping on your hip joints or your toes, and  no straining in your leg muscles.
Slide your elbows out to the side and place your open hands on your  abdomen or your hips; let the floor support your weight.
alexander `directions'
the above relaxation is combined with Alexander `directions'  to your body, it will bring about a lengthening of your spine, a widening  of the whole of your back, and a release and lengthening through the  musculature of your legs and arms.  Giving `directions' is a process  of `thinking into the body', and is best conveyed by a teacher.  Wilful  attempts to make this process happen might lead to your muscles contracting  further, instead of the release and integration which directing should  bring about.
The directions consist in thinking of the neck muscles releasing,  so that the head can move away from the shoulders in the direction  shown by the arrow (in fig.39), and in thinking of your back lengthening  and widening, and of your knees releasing `upwards' towards the ceiling  away from the hip joints and ankle joints.
After you have been lying down for some time, you should never get  up abruptly.  Instead, roll over on to one side first, letting your  eyes lead the movement.  Then you can get up gently.
Practised daily for 15-20 minutes, this develops greater poise,  and a noticeably improved awareness of bodily movements.