From Sri Mayapur Chandrodaya Mandir: HG Vaisesika Das

There is a way in which to perform tapasya in order to control the senses. It is a kind of combat between the practitioner and the desires and emotions within. But after all, we are sentient beings, which means we have emotions and we have desires. Therefore, the abject denial of desires and emotions can make the heart hard. From a hard heart, anger may arise. Therefore, we as Vaisnavas, perform yukta vairagya. That is, we perform austerities by rejecting anything that cannot be used in the service of Krishna.