The investigators will exclude patients from the baseline who have physical difficulties in performing a physical exercise program, pathological ECG, previous psychiatric illnesses, ongoing abuse, increased risk of suicide as determined by the GP, those under 18, pregnant women and those over 65 years of age. An additional exclusion criterion will be physical activity level at baseline exceeding one exercise occasion per week. Both people with and without ongoing treatment with psychoactive medication will be included. Supportive contact for example with a health center nurse is not an exclusion criterion but persons with ongoing psychotherapy will not be included unless the participants, as well as the GP, are willing to take a break in therapy for the duration of the 12 week study.