In my fifteen years as a clinician, I've worked predominantly with adolescents and young adults. I've always appreciated teenagers- there is such magic in that developmental period of trying on many different hats and identity exploration.
On countless occasions, I've had teenagers brought to my office by their parents, seeking support because their child isn't meeting the expectations set by someone in authority (the school system, or the culture at large, or the athletic coaches, or the parents themselves). They don't learn in a traditional way and don't want to go to school, or they don't want to participate in certain activities (ahem, ahem...sports...gym class, often). They aren't active at family events, or just don't like to go to them. They are too quiet and reserved, or too loud and effusive. They just want to read, or draw maps, or do some other solo activity. Or, they just want to socialize and be with their friends, and aren't taking their studies seriously enough. They don't dress right. They don't hang out with the right people. Etcetra, etcetera.