If a person believes they are doing the right thing, their brain will release dopamine (aka a reward) simply for acting within their belief system.
To be clear, I'm not trying to minimize or dismiss people's sacrifices. I still think they are noble
This is always true. No? Even self sacrifice, such as jumping in front of a bus, you deem to be the right thing - you chose an action because you believed it was a positive, for you, action. Just because you die doesn't mean you didn't still felt it was right, in that moment.
If you do something you do not believe is a positive it changes from charity to masochism. You're doing it to punish yourself. If you're not punishing yourself, you're gaining something (or net neutral, i suppose, but that's difficult to define).
edit: Though arguably even punishing yourself is self interest, as if you're punishing yourself it's because you want to.
One party can benefit and give nothing, while the other party still benefits.
I've literally never done anything charitable by your definition then, because i do it because it makes me feel good. I like helping others. Perhaps the only charitable companies or people are masochists? Hah
That is why raising "good people" is about helping them embrace the good feelings of being "selfless".
The only time i can think of (off the top of my head) where you would give but by no will of your own is to avoid negative outcomes like judgment from others. It's still, just like everything, in your self interest - you're just choosing to avoid pain rather than strictly acquire pleasure.
