देवद्विजगुरुप्राज्ञपूजनं शौचमार्जवम् | ब्रह्मचर्यमहिंसा च शारीरं तप उच्यते ||
deva-dvija-guru-prājña-pūjanaṁ śaucam ārjavam brahmacarya m ahiṁsā ca śārīraṁ tapa ucyate
Translation
Worship of the divine, the twice-born, the teachers, and the wise; purity, straightforwardness, chastity, and non-violence — these are called bodily austerity.
Interpretation
Krishna defines tapas (austerity) in its three dimensions: bodily, verbal, and mental. Bodily austerity is not self-mortification but: reverential worship of the divine and of teachers (recognition of the sacred in those who transmit wisdom), purity (shaucha — cleanliness of body), straightforwardness (arjava — alignment between inner and outer), brahmacharya (restraint of the senses in service of higher aspiration), and ahimsa (non-violence in all physical action). This is a remarkably wholesome definition — tapas of the body is about how one inhabits the physical dimension of life with integrity and reverence.