There are thousands of athletes who all aspire to become a champion like Mo Farah. To succeed in sport you have to commit yourself and be prepared to give 110% in both training and competition, and then you may just get the chance to prove yourself and break through to success. Many athletes come and go due to many factors, including injuries, other commitments and even boredom of the sport.
If you show dedication then you are far more likely to achieve your goals and progress to the next level.