It is very simple, very simple — simply thinking of Krsna. Smartavyah satatam visnur vismartavyo na jatucit. Always, simply if you think that Hare Krsna, if you think simply Hare Krsna Hare Krsna Krsna Krsna Hare Hare, Hare Rama Hare Rama Rama Rama Hare Hare, that is sufficient, even if you do not go into the Bhagavad-gita, if you do not go in the Srimad-Bhagavatam, simply as you are chanting. Krsna has given us the ear, and Krsna has given us the tongue. No expense, no difficulty. You haven't got to go to college and take degrees to become Krsna conscious. It is easy for the rich, for the poor, for the learned, for the fool, for the black, for the white, for the rich, for the poor, everyone. There is no distinction because Krsna is for everyone.
From Srila Prabhupada's lecture on Bhagavad-gita 4.12-13 — July 29, 1966, New York