He was justifying his existence, than which life can do no greater; for life achieves its summit when it does to the uttermost that which it was equipped to do.
God may allow His servant to succeed when He has disciplined him to a point where he does not need to succeed to be happy. The man who is elated by success and is cast down by failure is still a carnal man. At best his fruit will have a worm in it.
The concept of "mental health" in our society is defined largely by the extent to which an individual behaves in accord with the needs of the system and does so without showing signs of stress.