If a person asks you for money, do you give?

My friend asked me this question, and had to admit that normally I don't. I thought that was normal, so only felt a little guilty in my response.

Sometimes, however, I'll give generously. I explained to my friend that sometimes I'm asked for change, and I'll give $20 or $50 at a time.

It makes me feel good every time I do it.

The conversation ended there, but my behavior stuck with me.

I'm not sure that's what I should be aiming for when interacting with someone less fortunate than myself. In that situation, why is my feeling good a measure of success?