Figured that since the vast majority of us are young adults (while some are even older with some rust in your shots), that a discussion like this would be insightful.
Basically, before I make any decision, I always ask myself Wiifm (what's in it for me). If i'm about to spend money (wiffm). Before I decide whether or not I do someone a favor, Wiffm again.
It's not necessarily because i'm self-centered. It's just that doing so, IMO, forces people to actually sit and think about what they're doing instead of just doing something because they're expected to or because of impulses.