Hatha Yoga is the Yoga (union) of Ham (vital life force) and Tham (mental force). Hatha Yoga teaches how to conquer hunger, thirst, and sleep; how to overcome the effects of heat and cold; how to gain perfect health and cure disease without using drugs; how to arrest the untimely decay of the body resulting from the waste of vital energy; how to preserve youth even at a age of one hundred; without having a single hair turn grey, and how thus to prolong life in this body for an indefinite period with this extremes.