SB 11.12.9

Lord Kṛṣṇa here explains that it is very difficult to achieve His personal association, even for one who seriously endeavors to reach the Absolute Truth. The inhabitants of Vṛndāvana, such as the gopīs and cows, were always living with Lord Kṛṣṇa, and thus their association is called sat-saṅga. Anyone who is favorably living with the Supreme Personality of Godhead becomes sat, or eternal, and thus the association of such a person can immediately award others pure devotional service to the Lord. There is an austerity called cāndrāyaṇa, a fast in which one’s intake of food is diminished by one mouthful each day as the moon wanes and increased in the same way as the moon waxes. Similarly, there are painstaking ritualistic sacrifices and grueling studies of the Sanskrit Vedic mantras, which one may also teach to others. All these tedious activities cannot award the highest perfection of life unless one gets the causeless mercy of the pure devotees of the Lord. As stated in the First Canto of Śrīmad-Bhāgavatam (1.2.8):

dharmaḥ sv-anuṣṭhitaḥ puṁsāṁ
viṣvaksena-kathāsu yaḥ
notpādayed yadi ratiṁ
śrama eva hi kevalam
“The occupational activities a man performs according to his own position are only so much useless labor if they do not provoke attraction for the message of the Personality of Godhead.”