The Tapasya -generation of heat or energy referring to spiritual practice

Tapasya is practical  spiritual discipline. Literally it means the generation of heat or energy, referring to spiritual practice and its effect, especially the “roasting” of karmic seeds, the “burning up” of karma. It also refers to the heat necessary for the hatching of an egg. Without tapasya there is no significant spiritual progress.

Tapasya of the body

“Revering the gods, the twice-born, teachers [gurus], and wise men; purity, rectitude, celibacy, and non-violence: these are called tapasya of the body”

Pujanam is internal, so why does it come first in the list of physical tapasya? Because Krishna is not thinking of mere philosophizing or abstraction–empty words. He is thinking of action, of kriya, which creates positive karma in the form of purification and enlightenment. Puja is the word usually translated “worship,” and some translators use it rather than “reverence.” Worship in Krishna’s view is not mere verbal praise or glorification, but a living out of the interior attitude of reverence. So to reverence a spiritual authority is not to flatter, grovel, and publicize them or shower them with money and gifts. Rather, it is faithfully and seriously applying their teachings. Krishna speaks of four kinds who deserve our reverence: gods, twice-born, teachers, and wise men.

Devas are gods–not the Supreme God, but highly evolved beings who can affect our life. We might think of them as angels or saints, bodiless beings that interact with humans and help them in many ways. All viable religions have some form of devas.