Aerobic exercise, such as using the treadmill, walking or cycling, performed for 30-40 minutes, three times a week for at least a 12 week period, was effective at improving mental health outcomes in people with schizophrenia.
Reference: Stanton R, & Happell B. (2014). A systematic review of the aerobic exercise program variables for people with schizophrenia. Current sports medicine reports, 13(4), pp. 260-266.