A friend of mine wanted to give back financially, but not infrequently donating to some random charity. He became a member of https://www.givingwhatwecan.org/pledge/ (there might be other, similar projects, but if I remember correctly it's this one) and for a few years now he has been giving away 10% of his income as part of that community. Of course it doesn't have to be that much, but the pledge - even so it's not binding - and being part of a community helped to stick with it.