Bhagavad Gita 17.14देवद्विजगुरुप्राज्ञपूजनं शौचमार्जवम्।ब्रह्मचर्यमहिंसा च शारीरं तप उच्यते ॥

Tapas Austerity or selfdiscipline.Using the feet in pilgrimage to the sacred temples using the hands in cleaning the temples, in collecting the materials of worship of God, and in performing worship prostrations to the Brahmanas, preceptors and the wise continence and noninjury, constitute physical austerity. The body is used in the service of the parents and preceptors, the poor and the sick. This is also bodily austerity. That austerity which is done by the body is physical austerity. The physical body is the chief agent in doing such austerity. Hence this is called physical austerity. The practice of nonstealing and noncovetousness are also included in physical austerity.He who has realised I am Brahman is a wise man (Prajna). A Sudra also may be a wise man. Though Vidura was a Sudra he was a sage. That is the reason why the Lord has made a separate mention of the wise.Brahmacharya means control but not suppression of the sexdesire or sexforce. If the mind is filled with sublime thoughts by meditation, Japa (repetition of a Mantra), prayer, study of holy scriptures, enquiry of Who am I, and contemplation of the sexless, pure Self, the sexdesire will be devitalised by the withdrawal of the mind. The mind also will be thinned out. Suppressed sexdesire will attack you again and again and will produce wetdreams, irritability and restlessness of the mind