There's benevolent volunteering. Generally easy work that can affect someone's life for the better. Now, if that's not an ego booster on some level, I don't know what is.
Well, yeah, but there's also going to be a sense "of am I doing enough"? -- at almost any level you're willing to sacrifice in terms of time and money, you could always do a bit more, so knowing what "enough" is is anxiety producing.
Then do enough that you don't have the energy or time to think about it.
?? I wouldn't be that defeatist...
Less defeatist, more mystical. Besides, more productive to help people rather than worry about not helping people enough. ;b