Awareness is as essential to the practice of asana (postures) as it is to all yoga practices. The purpose of asana practice is to influence, integrate and harmonise all the levels of being: physical, pranic, mental, emotional, psychic and spiritual. At first it may appear that asanas are merely concerned with the physical level because they deal with the movement of different parts of the body. Actually, however, asanas have profound effects at every level of being if they are combined with awareness.
Awareness has many connotations, in this context, but it may be understood as consciously attending to:
Implicit in the concept of awareness is the idea of acceptance of any thought that comes uninvited into the mind; 'good' and 'bad' thoughts should be accepted equally, without judgement. In the final analysis, thoughts are energy (nerve impulses along a neuron), neither good nor bad. This awareness is essential in order to receive optimum benefits from all yoga practices.
Extract from Asana Pranayama Mudra Bandha (1996) by Swami Satyananda Saraswati.