In the ancient days, there was a popular belief that even the GODs were to come down to earth to perform spiritual practice. The reason is, when one does not have a physical existance, one cannot perform action. So long as human being is alive, so long as one possesses one's physical structure, one cannot but engage one's body in action.
One should not remain Idle for a second. Once a leader said, "Aram Haram Hyay" (Idleness is Harmful). Although many of his saying are not to be accepted as true, this one saying deserves acceptance.
A.V. Part-15, Chapter-8