One has to perform devotional service in full tapasya, austerity. One should fast on the two Ekadashi days, which fall on the eleventh day of the waxing and waning moon, and on the birthdays of Lord Krishna, Lord Rama and Caitanya Mahäprabhu. There are many such fasting days. Yogena means “by controlling the senses and mind.” Yoga indriya-saàyamaù. Yogena implies that one is seriously absorbed in the self and is able, by development of knowledge, to understand his constitutional position in relationship with the Superself. In this way one becomes fixed in devotional service, and his faith cannot be shaken by any material allurement.
(ACBSP. Srimad Bhagavatam 3:27:22. purport excerpt)