Help? What to be when I grow up?!?

Hey guys. I'm a sophmore in high school and everyone is always asking me what I want to be when I grow up, and I really have no clue! Everyone around me seems to have an ideas of what they want to be, and I really don't and I'm kinda freaking out! I feel like I'm running out of time! I love helping kids, especially underpriveleged kids, so maybe a teacher. However, I also LOVE sports and athletics and think it would be cool to work with athletes and help people more hands on physically(Maybe some type of therapy or trainer). I really just don't know though, but people keeps asking me, and I feel dumb when I just answer "I don't know yet" because everyone else seems to know what they want to be. Any advice?