Church youth groups often have opportunities for leadership - mission trips, leading groups of younger children in Vacation Bible School or on retreats. etc.
If you are involved in any kind of community service activities, ask to be in charge of something. Your school counselor may have a list of opportunities outside of school.
Also, check into attending Boy's or Girl's State in summer after Jr. year. Your school counselor should have information and our state's program has a website so you might check for your state. If you are able to attend, it's worth lots of points with the academies.