Answer with Explanation:
A person's self-confidence affects his way of thinking or his mental health. If he lacks self-confidence, he will most likely prevent socializing and trying out new things. He'll have negative image about himself that he's not capable enough to do great things. In the long run, this can affect his mental health. For example, he will become anxious every time he is invited to a social gathering. He will also feel depressed and unworthy because he cannot achieve his dreams due to his shyness. Such thoughts will overburden him and cause stress. Once he could no longer handle his stress, he could become mentally ill.
