Remember those group projects in school when one person did all of the work for the whole group? Remember thinking that once you got out of school and into the real world, that wouldn't happen any more? Just me? Well, I obviously failed to take into consideration the fact that the people you were in school with who were unable to do their part of the group project go out into the real world, too, and they continue to behave the same way. As Mother of Ken says, "this behavior works for them."
I am currently on the board of a non-profit organization--I'm actually the "president" of this board, if you will. In this capacity, I try to lead by example. I never ask anyone to do anything that I won't do, I help with every project that needs an extra pair of hands, I take the lead on things that no one else picks up, and if I say that I will do something, I do it. But this isn't about me and I'm not looking for recognition.
This is about me being sick of dealing with people who commit to do something and fail to follow through. Sometimes I feel like I'm in the world's longest lasting and worst group project. If you say that you will help with a particular project, then please follow through with that commitment. Do not whine about how busy you are, how difficult it is to fit this into your life, how much of an imposition this is for you, etc. If the aforementioned are true, then graciously refuse the request for help/participation in the first place.
This seems to be especially true for non-profit organizations. For some people, these organizations are clearly at the bottom of their list of priorities--always the first thing to be set aside when something better or "more important" comes along. Unfortunately, non-profit organizations are a hugely important part of maintaining civilized society, so someone has to step up and keep these organizations running smoothly.
Think about how much more we could do for the world if we all did what we said we would do--how many more people could we feed or clothe or shelter if we worked as an effective group?
I'm going to make a wild guess here and say that it is very likely that if you are busy, etc., etc., but you follow through with your commitments, good things will come back to you and you will still have time to fulfill all of your other obligations. Try it and see if I'm not right.