"Yoga has also been described as wisdom in work or skillful living amongst activities, harmony and moderation. Yoga is not for him who gorges too much, nor for him who starves himself. It is not for him who sleeps too much, nor for him who stays awake. By moderation in eating and in resting, by regulation in working and by concordance in sleeping and waking, Yoga destroys all pain and sorrow. This is steady control of the senses and mind."-- B.K.S. Iyengar
I've been reading Light On Yoga which was written in 1966- it's amazing how the resistance Iyengar experienced from those not exposed to yoga at that time was with yoga's spiritual nature... and today while that's somewhat improved (even in the "Texas Bible belt"), it's primarily viewed as a physical practice by most. And when we mention something in Sanskrit or yoga philosophy, we often experience some resistance.
Taking yoga beyond the physical in a way that brings out the light in yourself and others-- that's the challenge as a teacher. In the very first paragraph of his book, Iyengar describes yoga as union or communion. "It is the true union of our will with the will of God...yoking of all the powers of body, mind and soul to God."
Finding balance and union with our will and desires, and living out our own Truth.