this is the summary that the sages . . . sages means those who have undergone austerities, penance, and many tribulation for attaining perfection, they are called sages. "The sages, knowing Me as the ultimate purpose of sacrifice." Now if you perform austerities and penances, that is a kind of sacrifice. But yad icchanto brahmacaryaṁ caranti (BG 8.11).
In the Bhagavad-gītā you will find these are explained that yad icchantaḥ. Simply by desiring to go back to home, back to Godhead, one is supposed to follow the vow of brahmacārī. Brahmacārī, to live the life of celibacy, this is called brahmacārī.
So it has got so nice effect that if anyone from the birth to the death simply observe this life of celibacy, he is sure to go back to home. Simply by observing one rule: yad icchanto brahmacaryaṁ caranti (BG 8.11). It is so nice, brahmacarya. So this is sacrifice. Sacrifice means my senses dictate that "You enjoy," but I am not enjoying. I am not enjoying. This is sacrifice.