What qualifications do you need to become a Athlete?

There is no exact answer for that question. It depends what sport, what coach/board/team is going to sign you, and your build. The best advice I can give you is to practice, get someone/thing to motivate you like an athletic wife or a rivalry, get a good sleep, act with good composure at all times(you don't know when the press is watching), and go with your gut, but take your coaches decisions into affect.