If the roofing example didn't illustrate the point, let me try again.
Donate $100 to a literacy campaign, then volunteer for 30 minutes each week at a beneficiary elementary school to have a struggling reader read to you from one of the books your money purchased. You don't have to buy the book. You don't have to decide which books are purchased. You don't have to decide which student gets to read the books. But you can be involved enough to know that books were purchased and the students are benefiting. And your extra effort makes the $100 so much more fulfilling.
While it's great to get fulfillment out of your philanthropic activities, and it may incite you to do more; I hope you keep focus on the main goal: helping others.
A $3 donation (via Against Malaria Foudation) buys a bednet that protects about 2 people from malaria for 3-4 years. As a donor you don't get the satisfaction of meeting the individuals you help (though you can look at some photos). But is the fulfillment you seek important enough to donate to a charity that is a thousand times less efficient at converting dollars to benefits-for-others?
A good suggestion here is to "purchase your fuzzies separately". That is, give to the most cost-effective charities you can find, regardless of how fulfilling it feels. And then find the most fulfilling activity you can, and maximize that until you had your fill.
Donate $100 to a literacy campaign, then volunteer for 30 minutes each week at a beneficiary elementary school to have a struggling reader read to you from one of the books your money purchased. You don't have to buy the book. You don't have to decide which books are purchased. You don't have to decide which student gets to read the books. But you can be involved enough to know that books were purchased and the students are benefiting. And your extra effort makes the $100 so much more fulfilling.