Anxiety and depression
Understanding from one's surrounding and the knowledge about adolescent's difficulties can make it so that one rewards progress instead of focusing on the negative. If one is not aware of this, it is easy for the adolescent to be subjected to too much nagging and reprimanding which can lead to worse self-confidence and depression. There are several well-developed methods so that both parents and teachers can become better at this.
Good advice
There are many good tips regarding anxiety and depression. Among other things, what effect exercise, food and sleep may have for your wellbeing. Good information about this is available on the page Youmo.
Link to Youmo, English - feeling bad
Link to Youmo, English - tips for feeling better