So you must be very enthusiastic that "I shall preach the glories of the Lord to my best capacity." It is not that one has to become very learned scholar to become a preacher. Simply it requires enthusiasm: "My Lord is so great, so kind, so beautiful, so wonderful. So I must speak something about my Lord." This is the qualification, enthusiasm. You may not know Kṛṣṇa very perfectly. It is not possible to know Kṛṣṇa very perfectly. Kṛṣṇa is unlimited. We cannot know Kṛṣṇa cent percent. That is not possible. But Kṛṣṇa reveals as far as possible you can understand. So if we are sincere servant of Kṛṣṇa, utsāhā, and if we serve patiently, then Kṛṣṇa reveals.
The example is given in this connection: Just like a girl is married. Generally, a girl wants a child. But if she wants a child immediately after marriage, that is not possible. She must wait. She must serve her husband nicely. Utsāhān dhairyāt tat-tat-karma-pravartanāt, just like a faithful wife. Time will come she will become pregnant and she will have child. So niścayāt means... Just like the girl must know because she's married, because she has got a husband, that there must be a child. It is a fact. It may be little later.
Similarly, when you have entered into devotional service, bhakti-yoga, bhakti-mārga, your success is assured, provided you are enthusiastic and patient. Not that "Immediately I want a child," "Immediately I become fully Kṛṣṇa consciousness and perfect." No. There may be so many imperfections, because we are in the imperfect atmosphere. But patiently if you go on executing your duties in devotional service as it is directed in the śāstras and confirmed by the spiritual master, then rest assured that your success is guaranteed. This is the way. Utsāhān dhairyāt tat-tat-karma-pravartanāt. You must execute the duties.
Just like we have asked our student to finish sixteen rounds chanting, minimum. Sixteen rounds is nothing. In Vṛndāvana there are many devotees, they chant 120 rounds, like that. So sixteen rounds is the minimum. Because I know in the Western countries it is difficult job to finish sixty-four rounds or 120 rounds, like that. Minimum sixteen rounds. That must be finished. Tat-tat-karma-pravartanāt. This is the direction: observing the regulative principles. In this way, we must be abiding by the direction of the spiritual master and the śāstra. Then rest assured, success is guaranteed.