A wedding day photo or a health warning from a doctor will give most people a reason to stay in shape. Competitions are perhaps not substitutes for these life-changing events, but they are a part of the motivational tricks that you can artificially construct.
Keep Track Of Yourself
Just like in school, it is easy to track your performance when you have exams on a regular basis. Not only in sports, but in life in general, there is always a risk that you merely tread water. The next year ends up being just like the previous one. No Track. No change.
The Social Event
Team sports tend to be more social sports then individual sports. But competitions offer for all sport types an excellent opportunity to meet other people. Especially kids can improve their social skills and they can practice them in a comfortable environment.
A competition is one of the most defined points in time. The performance is judged right now. Not one minute before, not one minute later. You have to seize the moment. Just like public speaking, it's good to do it regularly. It's a mental skill to focus and to perform well on a specific day at a specific time. But this can build up unbearable nervousness as well.
Loosing Faith Before Loosing Face
Winning is not every thing, it is the only thing. Result orientated training can also discourage young athletes from competing. The fear of being compared to peers, or to historical performance, can surface easily. The same phenomenon is evident in adults. Competitions in sports, that have no historical reference to results, tend to attract Sunday athletes the best. When you know that your score can't be put in context of, let's say an Olympic record, there is no longer a risk of loosing face when competing. This is why a mud-run or a paddle-with-your-hands rowing competition can enlist loads of competitors.
It's difficult to win, but it's difficult to loose as well. If you hate to loose, then you might want to try your luck in a more unusual sport. Just let your accountability strengthen your health disciplines.