Yoga, an ancient but perfect science, deals with the evolution of humanity. This evolution includes all aspects of one's being, from bodily health to self realization. Yoga means union - the union of body with consciousness and consciousness with the soul. Yoga cultivates the ways of maintaining a balanced attitude in day to day life and endows skill in the performance of one's actions.
B.K.S. IyengarThe Yogi conquers the body by the practice of asanas, making the body a fit vehicle for the spirit. The Yogi knows that it is a necessary vehicle for the spirit, for a soul without a body is like a bird deprived of its power to fly.
B.K.S. IyengarDeath is unimportant to a yogi; he does not mind when he is going to die. What happens after death is immaterial to him. He is only concerned with life-with how he can use his life for the betterment of humanity. Having undergone various types of pain in his life and having acquired a certain mastery over pain, he develops compassion to help society and maintains himself in purity and holiness. The yogi has no interest beyond that.
B.K.S. Iyengar