You must fill every inch of your body with the asana from your chest and arms and legs to the tips of your fingers and toes so that the asana radiates from the core of your body and fills the entire diameter and circumference of your limbs. You must feel your intelligence, your awareness, and your consciousness in every inch of your body.
B.K.S. IyengarPranayama teaches the aspirant to regulate his breathing and thereby control the mind.
B.K.S. IyengarThe challenge of yoga is to go beyond our limits - within reason. We continually expand the frame of the mind by using the canvas of the body. It is as if you were to stretch a canvas more and create a larger surface for a painting. But we must respect the present form of our body. If you pull too much at once, we will rip the canvas. If the practice of today damages the practice of tomorrow, it is not correct practice.
B.K.S. Iyengar