Agree with CurryLover, just do something. If you think it's relevant and you get an opportunity, do it. I'm giving you the advice I wish someone had given me 4 years ago when I was 14. I've recently applied to be an Aircraft Technician and am relying purely on the interview to impress as I never did any air cadets, sports teams, or anything even remotely useful. I don't have anything to show I have the motivation, confidence or leadership skills to be in the RAF and this is definitely what I wish someone had told me. Prepare, prepare and prepare some more.