Concentrate on one part of the body at a time. How to do something with your hand. How to hold your spine. How to stand with your legs. Build up reflexes for each part. Rely on previously learnt reflexes to control other parts of your body, while you work on the next part.
or
Try to hold your whole posture in mind at once. Practice the gestalt. Look for global energy minima.
A combination of both is likely best, but the second one is less natural and needs more practice -- it needs total but relaxed attention, all mental registers devoted to the task. It's as much about stretching your mind as your body.
Japanese seem to be good at the second one. Well, they're good at something anyway... i'm fishing around trying to get a handle on what it is here. Maybe they're just naturally cool.