I’ve read that there is good evidence to support the premise that if you give to others in some way, it will enhance your own wellbeing, as well as the wellbeing of the receiver. On a purely common sense level, I have to agree with this because I seem to experience gratification when I give to someone and particularly so if I give to someone who I am very unlikely to see again (in other words, (s)he will have no way of repaying me). I can float through the rest of the day when I feel that I have been kind and so the positives for me far outweigh the gift given.
I’m not sure what the science or psychology is behind this personal reaction (and really, I’m not that concerned to understand it), but I am the first to admit that I feel so much better about myself if I’ve been able to help in some way as opposed to the other option where I feel guilt for neglecting to help when I know I probably could have done so.