Action, far more than words, will uplift them into a positive outlook. Singing, too, is a wonderful therapy. No need to explain to a child the reason singing is therapeutic. Just get him to sing. In music lies one of the best ways of bringing out the best in children.
Dance is another excellent way.
Body movements are closely allied to attitudes of the mind. It might also help children to make affirmations while moving their bodies. They can use the centering movements of dance to affirm, I live in peace at the center of my being. Certain outward-reaching dance movements might be used with the affirmation, I reach out with love to help my fellow creatures. Upward-stretching movements might be accompanied by the affirmation, I reach up to the heights within myself.