The reason to do ECs has nothing to do with college applications and everything to do with stretching yourself by developing skills you can't develop in class, engaging with people who are not part of 'your' set, testing the depth of your interest in areas you think you might like or exposing you to ideas/jobs/experiences you might not otherwise. If you can do some good in the world - give back - at the same time, that's nice too but not essential. Lots of kids have to work after school to help their families and that's fine too.
As for college applications, the importance of ECs depends on the type of school. Most schools don't care about ECs at all. Those that do, just want to see that you are an active member of your community, participating and contributing - you don't have to lead anything, but you might want to show some initiative in some aspect of your engagement. Any activity you care about and commit to is fine - sports, music, work, your religious community, your hobby, whatever... Most schools just want to know that you aren't a hermit. The highly selective schools (the ones that seem to figure so prominently on cc) that do care about ECs are not interested in people whose only EC involves joining or leading school clubs. They are looking for something that makes the applicant stand out from the otherwise highly qualified crowd and school clubs don't do that.
To your personal situation, join anything you think you'll enjoy but don't bother if it's just for colleges. A few activities in which you put more thought and effort is better than lots of activities you really don't care about. Just realize that there are lots of other more interesting things you could probably be doing, but it would take some initiative, creativity and willingness to take a chance on your part to find them.