Krishna teaches us, in the Gita, that it is better to do your own duty, however imperfectly, than to assume the duties of another person, however successfully.
Krishna advises Arjuna that he is born to be a leader, a warrior. This is his duty, his dharma. He must go out on to the battle-field and fight. He must trust in the Atman within (the divine spark) and trust in Brahman (the Supreme being).
Each one of us must find and follow our own path in life. We need to listen to our guru within, and not be swayed by external pressure and misgivings.