Mixed feelings about volunteering?

Even from a young age, I've always wanted to do community service, but never really got started. Now, in high school, with college hovering over my head constantly, I've been motivated to search for volunteer opportunities. I DO want to help people, but I can't help but think, "Great, this will be a nice addition to my resume" at the same time. I feel awful when I think like that, because I've always disliked people who just do things so it'll "look good." And I can't tell if I'm acting the same way or not. It's almost like my need to build my resume has tainted what should be an effort that comes purely from the heart. Has anyone ever felt the same way?