The lotus so far has taught me how a particular balance is struck: the sartorius muscles rotate the pelvis; rotation in the pelvis extends the hips; extension of the hips generates activity in the piriformis muscles; activity in the piriformis muscles rotates the sacrum contrary to the pelvis and a balance is struck. I can find the sartorius muscles, I can relax at the hips, I can pick up the activity of the piriformis muscles and I can realize a balance.
Having said that, I would hasten to add that for me the central practice is the location of the mind in space: this takes the form of “where is consciousness taking place, how does the occurrence of consciousness open the ability to feel?”.
My study now is just about sitting 40 minutes in the morning in the lotus without pain or numbness. Folks that start in the posture early, like about 7 years old, seem to be able to do this pretty well, but I didn’t start sitting at all until eighteen, and it took me 30 years from there to get to the lotus. Still, I don’t have much pain now, and most mornings I get up with a minimum of numbness in the upper foot. The clear feeling for the activity of sartorious and for the sink with extension that catalyzes activity in piriformis seems to be a turning point for me, but it’s not something I can take hold of: I rely on the location of mind in the lotus to open an ability to feel these things.