Extracurricular activities at school can help alleviate (reduce, eliminate) stress. Boys can also meet new people and make new friends. If they involve sports, extracurricular activities should focus on enjoyment, not just winning.
If your school doesn't have activities you are interested in, your local community centers and religious groups might have interesting programs for youth. Boys can also do volunteer work, such as at the local humane center, agencies that help people in need like The Salvation Army, or in a hospital.
Extracurricular activities are a great way to explore potential career choices. Volunteering in a hospital might give you firsthand experience working and helping people in that environment. Volunteering to tutor kids who need help with their studies and schoolwork might lead to a career in education, and it can also help you learn and practice schoolwork.