It has been said, "Faith without works is dead." I'd rather translate it so it is clearer. "Faith that is not put into action is useless and meaningless." We can't say that we have faith and then not do the actions that our faith proclaims.
A person can have faith that he can be a great doctor, but if he doesn't put in the actions (going to school, diligently studying, etc), his "faith" is useless.