And if there is nothing else, you can always sit down and chant Hare Krishna Mantra. 16 rounds daily is the minimal requirement, but you should chant Hare Krishna as much as possible. And follow all the regulative principles strictly. Read all our books, attend classes and go for street Sankirtana. In this way be engaged in Krishna's business 24 hours and you will be happy and in the end you will go back home, back to Godhead.
Letter to Kirtika (Judith Cornell), 21 May, 1971