As a volunteer, sometimes I catch myself in the middle of the chaos of the event I'm volunteering for, wondering why I signed up for this? It's not until well after the event has ended, when I'm connecting with my fellow volunteers after the event, that I figure it out.
Working together is part of the human experience. We are social creatures who love helping one another - even if we don't always feel like it at the time. Once you've done your volunteering job, you feel better. You've made a difference in someone elses' life and that changes your life too. Have you noticed you feel a little more positive about the world after you've worked with a bunch of people at an event? Even if it takes you a while to realize it, you feel lighter, you look back on even the worst things with a positive light. Because you did your part in helping the community, your community, and the world. It may not feel like you've done something big, but you have impacted another person, and they go on to impact others, and so on.
Eventually, everyone is doing good things, and helping one another. Always remember, you make a difference. It may seem small and insignificant to you. To someone else, you may have just altered the course of their life forever - in a wonderful direction.