[...] And if you simply make this determined vow - "I shall not allow my tongue to taste anything not offered to Krsna and shall always engage my tongue in chanting Hare Krsna" - then all perfection is in your grasp. All perfection. Two simple things: don't eat anything not offered to Krsna, and always chant Hare Krsna. That's all.
Srila Prabhupada, from The Quest for Enlightenment