I completely agree with this opinion. Many teenagers could make a great contribution to society, if they were to volunteer in some communities. Also it may reflect on their future, they may gain admission to university easier, because of their better portfolio and work experience.
First of all, teenagers can help other people like old generations in nursing homes. Workers in nursing homes usually may have too many things to do, in these situations they really need some help of somebody who have a lot of energy, like a teenagers. Volunteers can help them by entertaining the elderly, bringing them pills, checking their pressure, Puting them to bed at night time, and wake them up in the morning and so on. And also most of the elderly probably would love to spend some time with young generation.
The second thing where teenagers can help other people and themselves is camping with children. Being camp counselor is really interesting, and healthy. Most of the camps are in mountains, where teenagers can get fresh air vitamin D from the sun. Also it develops the leader and social skills of teenagers, due they need to look after children.
I suppose that most teenagers myhate try to work during the holidays or after school. They have a lot of energy due to their age, and I believe working is the best way to spend it. Also It is very important to gain work experience as early as possible nowadays, and volunteering copes with this task very well.