In your discipline, if doubt comes, let it come. You do your work and let doubt carry on with its work. And let us see which gives up first!
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. IyengarMany ask me whether pranayama ... postpones old age. Why worry about it? Death is certain. Let it come when it comes. Just keep working. The soul has no age. It doesn't die. Only the body decays. And yet, we must never forget the body, since it is the garden we must cherish and cultivate.
B.K.S. Iyengar