He needs physical activity directed towards an external goal; not doing something for himself (although he will be), but for other people, animals, the planet, a political cause, neighborhood clean-up - whatever. Once he finds that cause and starts working, setting goals (however small) to accomplish in that cause, and accomplishing them, the energy itself will build and grow, just like his non-depressive cognitive patterns. And every time he finds himself thinking negative, defeatist thoughts, he should imagine one of those giant red stop signs and STOP! It's another habit to develop, and gets easier and more effective every time he tries it.