Inclusion Criteria:

• * chart diagnosis of schizophrenia, schizoaffective disorder, bipolar disorder, or recurrent major depressive disorder with psychosis;
• * age 18 and over;
• * BMI \>= 30.0 (obese); and
• * ownership of a phone running Android OS or iOS (iPhone).

Exclusion Criteria:

• * chart diagnosis of dementia;
• * history of bariatric surgery;
• * pregnant and nursing mothers;
• * patient has a conservator/legally authorized representative who makes their medical decisions;
• * psychiatric hospitalization during the month prior to enrollment.
• Additionally, we will follow the American College of Sports Medicine recommendations for health screening and risk stratification in preparation for starting a moderate intensity exercise program to ensure that participants enrolled are capable of safely engaging in the app's recommendations regarding physical activity. Specifically, all potential participants will be given the Physical Activity Readiness Questionnaire (PAR-Q), a screening tool often used in weight management trials. If they endorse symptoms or major signs suggestive of cardiopulmonary disease (i.e., angina, anginal equivalent, dyspnea, syncope, orthopnea, edema, palpitations or claudication), which is a score \>=1 on the PAR-Q, they will need clearance from a VA physician before enrolling.