I trained for a marathon with another, but similar group: Train to End Stroke. Our coordinator was extremely helpful and outgoing with the fund-raising, and the training, which was actually pretty aggressive during the week and conservative on weekends, certainly prepared me for the race. I expected to form closer bonds with the other people who were on my "team," but not many people were my age. I think a majority of the participants also joined with a friend or two, so didn't need to be super outgoing and friendly. I always attended the weekly group trainings, which was a huge help to me (The commitment got me out of bed early Saturday mornings!) If you really believe in the cause, I think it's a great way to help.