Kṛṣṇa does not say that you change your occupation. Just like Arjuna. He is a kṣatriya. His business is to fight. The division of human society, Brāhmin, Kṣatriya, Vaiśya and Śūdra, is very scientific. A Kṣatriya is meant for fighting. A Brāhmin is meant for intelligent work. A Vaiśya is meant for business. A Śūdra is meant for labor.
But because there is no such division, people are not trained from the very beginning. Therefore a Śūdra is called by the draft board, "Come on," to fight. Now, how he can fight? He is not a Kṣatriya. So they are flying away. They're taking visa for another country and going away. How he can fight? He is not Kṣatriya.
So Kṛṣṇa said Arjuna that, "You are Kṣatriya." He did not say . . . Kṛṣṇa wanted . . . Arjuna wanted to become a false Brāhmin. He said: "Oh, I shall become nonviolent, and even though I don't get my kingdom I shall beg like a Brāhmin and shall live away. Kṛṣṇa, don't ask me to fight." This is false Brāhminism. "Oh," Kṛṣṇa said: "you are Kṣatriya. You must fight." It cannot imitate a Brāhmin’s business. This is false.
So anyone has got a particular duty, as I explained in the beginning, so he, let him do that particular duty. He doesn't require to change. Sva-karmaṇā tam abhyarcya (BG 18.46). But try to see whether by execution of your particular type of duty you have satisfied God. That is your perfection.