I play both competitive soccer and AAU basketball. I plan to continue both as I enter high school next fall. As long as your schoolwork and energy levels don't suffer, don't worry. I would not be surprised to hear you're even more disciplined in school and more energetic because of your athletics. Stand with palms on sides of thighs.
Shrug shoulders up, back, around.
Do 10-12 repetitions. Stand with fingers laced. Extend arms up, lifting rib cage. Hold a few seconds. Bend arms down behind head, keeping elbows close in.