To increase the preaching we have to increase our desire to preach. It is very difficult to preach when we don’t have a strong desire to do so. When we increase our own desire to preach, we will also increase the desire of others; because by preaching, we will both give them the message that others need to hear and increase their impetus to spread it. In general we see that it is not usually compassion that motivates devotees to go out and preach. Sometimes we are motivated by the desire for recognition more than by our compassion. Perhaps we are motivated by the desire for profit. There may be so many impure motivations. If we want to preach effectively, we will have to strengthen and purify our desire to share Krishna consciousness with others.
(SB 4.11.8-10 9.20.1995, Kaunas)