Since you're a girl (at least judging by your name), there's a cheerleading group called SCLS. I don't know if you're interested in cheerleading, but it's something linked to athletics and it might be up your ally. You need to have been in SL for 30 days. I joined on Halloween, so I might just make the cut for December. We'll see!
If you're into lifting weights, stretching, gymnastics bars, punching bags, you should check out some gyms. Alpha Gym is the one that I frequent most often.
