Pubescent boys must know that they have power over some things in their lives. Some things they can’t change, but with certain issues, they can do something about them and influence or determine the outcome.
With things you can't change, you must learn to accept them and do the best you can.
Surround yourself with good friends who don't put you down and avoid toxic people. Toxic people put you down, criticize you a lot, and don't have your best interests in mind. You also want to do at least some things at times that are out of your comfort zone.