Freedom does not come so automatically. One has to work for it seriously. It is like a treatment during diseased condition. The patient with fever or some other painful disease has to undergo some penance for its remedy. To remove painful boil on his body he has to undergo surgical operation. This is called tapasā. Tapa means painful condition, tapa. Just like temperature. If you are put into high temperature, 110 degree, then it is very intolerable for you. It is very painful. Even for Indians—who are born in India in tropical climate it becomes sometimes intolerable. And in some cold places like Canada etc they can tolerate cold forty degree less than zero. So it is a question of different condition of life.
Formerly sages used to go to the Himalayan mountains during peak cold or to places of scorching heat. They ignite fire around them in places of high temperature and scorching heat before sitting for meditation. And during pinching cold they will sit under cold water to meditate. So for God realization formerly people used to undergo such severe type of penances but at the present age we are so fallen even to follow the four principles of No illicit sex, no intoxication, no meat-eating, no gambling.” These are the items of tapasya for advancing in Kṛṣṇa or God consciousness. It is actually not difficult. If one can practice to sit within the water up to the neck in chilly pinching cold, it is not also difficult to give up Bad habits by simple devotional practices. If one wants to realize the Supreme they must agree to certain type of tapasya. Otherwise it is not possible.
Ref >> Srila Prabhupada Vani.