I was once passed by a chugger, they asked me to sign up to their charity, I politely declined, they called out after me “You should it would make your feel good”. (needless to say I was astounded)
But she was right. You have probably read of this but its worth repeating :
Positive psychology expert, Martin Seligman carried out an experiment called “Philanthropy versus Fun”. In the experiment he divided up his psychology students. One group engaged in pleasurable activities (like going to see a film, eating ice cream) while the other group engaged in philanthropic activity (eg volunteering)
Seligman found that the happiness afterglow of the fun was nothing compared to the lasting happiness of doing altruistic acts. The reason, Seligman suggests, is that kindness is a gratification. ‘It calls on your strengths to rise to an occasion and meet a challenge. Kindness is not accompanied by a separate stream of positive emotion, like joy; rather, it consists in [sic] total engagement and in the loss of self-consciousness.’
Of course I don’t recommend that you write or call your donors and tell them they should do good because it will make them feel good!