I hate the way I look.?

Im a sophomore guy in high school. I'm like 5-11 and around 150 pounds. I'm really active and play a lot of sports and go running a lot but Im still not thin like my friends. I'm still a little chubby even though I run and do sit-ups and pushups a ton. How can I get thin? And I just dont feel good about my face, its kind of round with big cheeks and a little curly hair. How can I gain confidence?