1. Sport helps to study better (while doing sports, organism produces endorphines - hormones, that make thinkin process easier)
2. Sport keeps you fit. And if you're fit, you will have a good motivation for doing anything.
3. Sport makes you more serious, you also become more independent and self-confident.
4. Sport may be fun. Isn't it cool to spend evening playing basketball with your pals?
5. Sport bring people together. If you don't have friends - you'll find them, if you're not sociative - you'll stop being shy.