To brain it is not yoga asanas (postures) but rather various life situations. Being able to remain calm while performing various levels of postures using techniques of breath to keep mind withdrawn from external world, it is your body performing using power of your mind to present itself to its own consciousness ...
Yogis practice yogasanas regularly (imitating in postures various creatures or thing such as boat, dog, crow, eagle etc using his flexibility and strength part of mind in order to unite himself with his inner consciousness. Over time so that he can sit longer in meditation without bodily aches or external environment. )