Concentration; by focusing solely on the breath and body our thoughts become like clouds passing in the sky of the mind. Without mental chatter the Ego (Asmita) drops away and the veil of Avidya is lifted.
Training the mind to lose the ego and the separation that comes with it is the process of knitting together that severed communication between mind and spirit. We begin to unlock the mental problems creating the illness. We learn to control the mind away from addictive habits.
Drishti (focused gaze) during asana forces the mind to stop wandering and forces ego aside.