Major depression is one of the most prevalent and most disabling emotional disorders. Its impact is pervasive, affecting social, individual, and biological functioning. For individuals with depression, negative thinking pervades views of the personal past, the current self and the personal future while lack of interest and anhedonia reduce engagement in activities that used to be experienced as enjoyable. These psychological symptoms are accompanied by dysregulations in a number of physical systems, with symptoms such as fatigue and difficulties concentrating undermining the ability to deal actively with the challenges of everyday life.