Because a nondevotee has become a devotee, he is practicing how to simply accept Krsna’s orders. But by his previous habit he’s still engaged in “Do it” and “Do not do it.” That is his previous habit. Just like this fan is running. You take out the switch, the current is stopped, but it’s still running, at least three, four rounds. So similarly, if you have taken to Krsna consciousness, your that current of “Do it” or “Do not” is stopped, because you have agreed to do only what Krsna says. If you have actually decided like, then you are free. There is no more current of “Do it” or “Not do it.” But because you were habituated in your past life to this “Do it” or “Not,” sometimes it is found. Therefore Krsna says,

api cet suduracaro
bhajate mam ananya-bhak
sadhur eva sa mantavyah
 sasvad bhavati dharmatma
 [Bg. 9.30]

He has got little practice of these nonsense things. But if he sticks to Krsna consciousness, this will be stopped very soon. That is the only remedy. So a devotee means he has taken vow before the spiritual master, before the fire, before… If he sticks to his principle, then he’s free, even though some bad habits found due to his past behavior. That will be stopped. But he must stick. Bhajate mam ananya-bhak. That must stick. Krsna consciousness must continue. Everything will be corrected. And if there is slackness in Krsna consciousness, then again he’ll fall down. If you have determination, maya will put forward so many impediments, and with all sufferings, if he remains determined in Krsna consciousness, then life is success. A man is habituated to smoke. He has given up, has promised no more smoking, just like our students. Now he’s put amongst some friends, they are smoking. But he has bad habit, he’s thinking, “Why not smoke?” And if the friends offer, “It is friends. Who is going to see, your spiritual master?” “Yes.” That is possible. But if he comes to his sense again, “Oh, what I have done?” If he repents, “I promised it before my spiritual master, before God, before fire. Now I’m doing this?” that repentance will help him. And if he thinks that “I’m doing it. My spiritual master is not here, let me fall to it,” then he is finished. Then he is finished. If he repents for the
wrong he has done, then he’s excused. Otherwise finished.

(Srila Prabhupada — August 11, 1976, Tehran)