The practice of the limbs of yoga leads to the remission of impurities and the radiance of penetrating knowledge, bringing the aspirant towards discrimination from knowledge. (YS II.28)
Yama is disrupting systemic harm, to participate in facts of people not being deprived of what they need, personal boundaries respected and no appropriation.
Postures to be assumed should be both still and pleasant.
Continuous effort and endless relaxation are the twin attainments (of āsana, in particular, or Yoga in general).
On the realization of this (the perfection of posture), control of breath should be practiced. It consists in breaking the mal-flow of inhalations and exhalations.
When the mind withdraws from its objects and resides in its own form, then in a like manner the sense organs imitate the mind by withdrawing from their objects.