Youth is not a time of life--it is a state of mind. It is not a matter of ripe cheeks, red lips and supple knees. It is a temper of the will, a quality of the imagination, a vigor of the emotions. It is freshness of the deep springs of life. Nobody grows old by merely living a number of years. People grow old only by deserting their ideals. Years wrinkle the skin, but to give up enthusiasm wrinkles the soul.
-- Swami Bua, famed yogi who lived approximately 120 years