I used to work for the YMCA as a camp counselor, and also volunteered a few weeks of my time before every summer to get the camp ready. Every volunteer I met was either an employee or former employee, very ocassionally someone who was a camper when they were a kid or a parent of a current camper. The trick is that many of us actually believed in the mission and so were willing to do that, and regarding the camp in particular it came with a community that everyone who stayed loved and wanted to contribute to.

Of course there's a fine line between this attitude and being exploited by your employer for free labor. In this case I think it helped that everyone knew it wasn't a career for most of us. You work for a few summers in college and then you graduate and if you want to stay a part of the community you continue volunteering from time to time.