This is a mental exercise that, I feel, gives an assocciation towards the concepts of condense/expand and the feeling of yin within yang and the yang within the yin.
It's a mental exercise with no physical movement so you can sit, lie, or stand. First settle into yourself, relax and follow the breath. Imagine your center (dantian) and feel as if the breath is drawing inwards towards it on the in-breath and expanding outwards (towards the extremities) from it with the out-breath do this long enough until you really feel it.
Then switch the mental movement so that you expand on the in-breath from the center and draw in towards it on the out-breath, do this til you feel it. Play with the different feelings switching between the two for a while.
Then try to combine them.
The next step would be to feel the same whilst doing some of the movements we train.
I'd be interested in anyone's comments.
Steve