Strength Comes from Within, Not from the Muscles
Concentration on the muscles, as in the practice of mechanical physical exercises, tends to make one think of himself as a physical being only. [Hatha Yoga] instructions teach the science of concentrating on the inner life energy and will power and thus awakening one’s consciousness of his subtle spiritual nature. Strength comes from within, not from the muscles. Life is sustained from the power within; it does not depend solely upon food or exercise.