The yoga system, hatha–yoga system, is meant for this class of rascals, ajita. Yoga indriya–samyamah. Real meaning of yoga means controlling the senses. So because everyone is ajita–sad–varga — ajita means not conquered — so those who are too much addicted in the bodily concept of life, for them this hatha–yoga is prescribed. The purpose is to control the senses, not that to reduce fat or something else. No. Real purpose is yoga indriya–samyamah. Because unless we control the senses, we remain in ignorance, blind, and go on.
From Srila Prabhupada's lecture on Srimad-Bhagavatam 6.1.52 — August 5, 1975, Detroit