One of my favorite essays is Personal Integrity by L. Ron Hubbard
I try to live up to this in all aspect of life.
I think it applies to so many areas - relationships, self-esteem, how hard you work on the job (are you punching the clock or are you trying to make a difference) and one's own spirituality and religion beliefs.
Here's an interesting discussion on the latter.
Beautiful Horizons: The Religion Discussion