Why am i always tired?

I am a freshman in high school and i feel tired all the time. Im not sure what the problem is because Im getting plenty of exercise, I eat nutritious food and i never eat junk food, and i go to bed around 8 to 10 most of the time. But, I think one of the problems might be is that I'm getting too much exercise because i wake up at 6:30 every school day and workout from 7:30 to 8:15, and then after school i either have football or baseball practice (depending on the time of year) right after school until 6:30 or 7:30. Then when I get home I eat dinner, and do homework if i can stay awake. And this is beginning to affect my grades because i can't stay awake during cl, and i don't have any energy to take notes or even try. If you know why I am so tired and exhausted please let me know.