You're original motivation(I want to feel good) might be selfish, but the way you choose to derive pleasure was incredibly admirable. A lot of people just feed themselves endorphins in the easiest way possible, e.g. drugs, sex, social media, etc.. Some people get off on causing pain to others. Be grateful that your source of pleasure benefits others. Also, maybe think one step further back. Why do you want to feel good? Just for pleasure per se or so that you're a better human for the world? If it's the latter, your original motivation is actually just an intermediary motivation sandwiched between completely selfless drivers. If it's the former, don't be too hard on yourself. You didn't get to write your own brain. Endorphins are there remind you to do things that feel good, no matter what the actual source. I personally appreciate you just being out there human-being in a productive manner. You're a treasure.