Depression rates are rising at an alarming rate with each generation having higher rates of it. Dr. Stephen Ilardi says that depression is a disease of civilization. So to avoid depression, you should become uncivilized-- just kidding (kind of).
Learn about the many physical causes of depression and how to correct them. Dr. Ilardi says "exercise is medication." Then also learn about non-physical causes of depression and how depression may actually help you. See The Purpose of Depression