As long as we keep ourselves pure for preaching, then we shall have all good results–of that there is no doubt. One thing, make certain that your routine work is going on nicely–chanting 16 rounds, rising early, cleansing, street Sankirtana, etc.–then all other programs will be successful. If routine work becomes slack or neglected, then all other attempts will fail. We should always cling to the Lotus Feet of the Supreme Personality of Godhead by following very strictly the routine work of devotional service, and then we shall qualify to associate with the Lord by becoming very pure, and that is our real happiness, know if for certain.

(From Srila Prabhupada's letter to Cyavana – Bombay 26 December 1971)