The greatest obstacle to being heroic is the doubt whether one may not be going to prove one's self a fool; the truest heroism is to resist the doubt, and the profoundest wisdom to know when it ought to be resisted, and when it be obeyed.
Don't just fight in the North or the South. Always imagine every battle in your mind, where everyone is both your enemy and your friend, and all possible events happen simultaneously. That way, nothing will take you by surprise, and everything that happens will be something you've already imagined.