A career in sport, ah.... So, don't do football, rugby, baseball, US football, weightlifting, tennis, wrestling, track and field, or practically anything else. Everything has it's problems. Might as well try and be a bike rider, at least they get tested and results don't get covered up because there's too much money involved. You can do it clean right to the top level. This takes, however, talent, a shedload of hard work, dedication, self-denial, and a steely determination. After all that, if you don't make it, just race at a lower level, be content, and able to look your family in the eye and tell them the truth that you did everything you could to succeed, and at least you gave it everything.