While in Seattle today at Green Lake park, I sat on a bench with a plaque that read, "This bench is a gift from a family that loves Green Lake." What struck me about this plaque is that it is anonymous. There is no credit given to the giver. For this person/family, the reward was in giving not being publicly recognized as a giver. True generosity doesn't care about TV cameras and recognition. The mere opportunity to show love is reward enough.
Maybe this is why Jesus encouraged His disciples to give in secret? When we make a big public show of any donation, it can be real hard to keep our motives pure.