You find 200 dollars on the floor, what do you do?

I have a hard time getting off the fence regarding karma. On one hand, it surely helps believers lead "better" lives, creating a better society in general, but on the other, doing good things for a personal reason isn't exactly good will in my book. I prefer to be a d'ick (keeping the money) where I normally can't be a saint (going through all lengths to find the owner, regardless of conditions) instead of forcing myself to be kind because of karma.