”Through the performance of yoga a yogi receives super natural power over material elements such as earth, water, fire, air and ether and thus becomes eligible to control these five elements through yogic powers. Being purified by the fire of the yogic process a yogi’s body does not become afflicted with any disease, nor becomes old nor dies.”
prthvy apyatejo ‘nila khe samutthite
pancatmake yoga -gune pravrtte
na tasya rogo na jara na mrtyuh
praptasya yogagni-mayam sariram
PURPORT BY SRI KRSNA BALARAM SWAMIJI
This verse indicates that a yogi is able to show yogic perfection externally. The potency of spiritual practice is such that a yogi can perform such surprising acts that a normal human being cannot do. If a normal human performs such acts death will occur. With spiritual power of yoga a yogi can bury his body underground and live for a long time without breathing. He can submerge under water and meditate for a long time without breathing. He can sit in the center of a blazing fire for a long period of time and not feel heat or get burnt. He can stop breathing completely and can control his air movements in his body. He can disappear from a place and no one will notice his disappearance. Such mystic feats a normal person will not be able do. This all comes by the power of performing yoga successfully.
[Svetasvatara Upanisad, 2.11, KBS0017]