Good Deed?

Today I was at Fred Meyer. When I was checking out at the cash register I saw a $100.00 bill folded on the ground at my feet. For a half a second I thought about picking it up and putting it in my pocket. I certainly didn't do that and turned it in to the cashier. I felt really bad the whole way home that I even thought about keeping it. Whoever dropped it probably will have no idea where they dropped it and never retrieve it which makes me wonder what Fred Meyer will do with that $100.00 bill if nobody claims it. Still, that doesn't really matter in terms of turning it in because it wasn't mine to keep. Although I know I did the right thing I still feel bad because I briefly contemplated keeping it. I seem to do this a lot - I do what I really think is right but, because I contemplate the "wrong" decision I still feel bad about my "right" decision. I don't know if that make sense but is it still a good deed if I thought about doing the wrong thing? Do other people automatically think to do the right thing or do a lot of people initially contemplate doing the wrong thing?