More on prana: a.k.a. Are you doing yoga or are you being taken for a ride?
Hatha Yoga Pradipika 2/42 and 4/20
When pranavayu flows in the middle passage, sushumna nadi, mind becomes still and thoughtless. This steadiness of mind is called Manonmani. After attaining this state all practices are useless for a yogi.
Hatha Yoga Pradipika 2/2
Gheranda Samhita 1/90
When prana moves, the citta (mental forces) also move. When Prana is still, citta will also be still. By this stillnessof pranavayu, a yogi attains steadiness, so one should control pranavayu.
Hatha Yoga Pradipika 4/21, 4/23, 4/25
When the mind is stillor restrained, the pranavayu will also be still or restrained and vis versa. When both are active all the senses will be active, so control them for the attainment of moksa.
Bhagavad Gita 4/29
Some yogis merge pranavayu in apanavayu, some merge apanavayu in pranavayuand others sytop the movement of prana and apana vayu and become masters of pranayama.
Gheranda Samhita 1/41
Apana vayu residing in the lower region of the body attracts prana vayu from the upper part of the body and vis versa. When both are united this is called yoga.
Are you acomplishing yoga or are you being taken for a ride?