Tunca, I know how you feel.
I try to tell you that I, too, sometimes feel left out.
That I, too, want to do things that I am not capable of.
I want to run faster, and hit a soccer ball with decent accuracy. I want to climb high and be the one picked first for a team.
I am really, truly sorry that I cannot make you feel better about it, though. There will always be such sucky times and you probably will be mad at me for telling you so.
One thing I can tell you for sure is if you insist on playing soccer with 6th graders, I just cannot watch you get kicked in the shins or get smashed in the head with the ball travelling 60mph. I simply will not watch anymore. So there.