Yoga Sutra 3.40

samā-jayāt-jvalanam

Radiance results from the triumph of the vital force of assimilation and balanced distri-ution

The samāna-vāyu is located in the umbilical area and saṁyama on the same ensures healthy digestion including the regulation of body temperature/digestive fire.

Fire is responsible for radiant energy and flamboyance and that healthy glow in people. 

Damian Cadman-Jones is an authorised teacher of Prana Vashya Yoga™