What is that buddhi-yoga? Krsna says, tesam satata-yuktanam: "Persons who are twenty-four hours engaged," satata... Satata means always. Engaged. What kind of engagement? Bhajatam priti-purvakam. This engagement means always trying to render some service to the Lord. How? Priti-purvakam: "with love and faith." Not that "Oh, I have to do it? All right, let me do." No. "Oh, I have to do it? Let me do it nicely." Unless there is love, you cannot do it nicely, any matter.
Lecture oт Bhagavad-gita 2.39, London, September 12, 1973