A third factor, that of Respect for Responses

4. So Āsana are considered as voluntary phenomena,
like writing with your opposite hand.
Thus, it is an action which requires conscious control.

However, when you are used to going from everyday
postures to Yoga Āsana they become automatic in use.
Thus, they become involuntary.

Āsana Mudrā & Prāṇāyāma
– Collected Viniyoga of Practice Planning Principles

Āsana Mudrā & Prāṇāyāma
– Collected Practice Planning and Practice Theory Questions