Tapas (Hinduism, Yoga)

By practice of fasting, physical austerities, observance of vows, the will is strengthened and association with the physical body weakened. The lower nature is purified and brought under control in a way analogous with the refining of gold by fire. Tapas is said also to lead to occult powers and siddhis. Not all austerities and siddhis are considered worthy – some vows may be foolish or demonic and the misuse of siddhis by the morally or spiritually undeveloped brings trouble in this life and the next.

One of the five virtues, components of niyama (self-discipline).