Srimad Bhagavatam Canto 04, Chapter 28, Text 37

SB 4.28.37

 ksut-pipase priyapriye
sukha-duhkhe iti dvandvany
 ajayat sama-darsanah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Through austerity, King Malayadhvaja in body and mind gradually became equal to the dualities of cold and heat, happiness and distress, wind and rain, hunger and thirst, the pleasant and the unpleasant. In this way he conquered all relativities.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Liberation means becoming free from the relativities of the world. Unless one is self-realized, he has to undergo the dual struggle of the relative world. In Bhagavad-gita Lord Krsna advises Arjuna to conquer all relativities through tolerance. Lord Krsna points out that it is the relativities like winter and summer that give us trouble in the material world. In the winter we do not like taking a bath, but in the summer we wish to take a bath twice, thrice or more a day. Thus Krsna advises us not to be disturbed by such relativities and dualities when they come and go.
The common man has to undergo much austerity to become equipoised before dualities. One who becomes agitated by the relativities of life has accepted a relative position and must therefore undergo the austerities prescribed in the sastras to transcend the material body and put an end to material existence. King Malayadhvaja underwent severe austerities by leaving his home, going to Kulacala, taking his bath in the sacred rivers and eating only vegetables like stems, roots, seeds, flowers and leaves, avoiding any cooked food or grains. These are very, very austere practices. In this age it is very difficult to leave home and go to the forest or the Himalayas to adopt the processes of austerity. Indeed, it is almost impossible. If one is even advised to give up meat-eating, drinking, gambling and illicit sex, one will fail to do so. What, then, would a person do if he went to the Himalayas or Kulacala? Such acts of renunciation are not possible in this age; therefore Lord Krsna has advised us to accept the bhakti-yoga process. Bhakti-yoga will automatically liberate a person from the dualities of life. In bhakti-yoga, Krsna is the center, and Krsna is always transcendental. Thus in order to transcend dualities, one must always engage in the service of the Lord, as confirmed by Bhagavad-gita (14.26):
mam ca yo ’vyabhicarena
 bhakti-yogena sevate
sa gunan samatityaitan
 brahma-bhuyaya kalpate
“One who engages in full devotional service, who does not fall down in any circumstance, at once transcends the modes of material nature and thus comes to the level of Brahman.”
If one is factually engaged in the service of the Lord, bhakti-yoga, he will automatically control his senses, his tongue and so many other things. Once engaged in the bhakti-yoga process with all sincerity, one will have no chance of falling down. Even if one falls down, there is no loss. One’s devotional activities may be stunned or choked for the time being, but as soon as there is another chance, the practitioner begins from the point where he left off.
Srimad Bhagavatam Canto 04, Chapter 28, Text 35-36
Srimad Bhagavatam Canto 04, Chapter 28, Text 38