Exercise and Olanzapine-samidorphan

This study looks at whether adding a structured exercise program to a new antipsychotic medication (olanzapine-samidorphan, which is designed to cause less weight gain than standard olanzapine) helps reduce weight gain and metabolic side effects in people with schizophrenia, schizoaffective disorder, or bipolar disorder. **You may be eligible if...** - You are between 18 and 65 years old - You have a DSM-5 diagnosis of schizophrenia, schizoaffective disorder, or bipolar disorder - Your BMI is between 18.0 and 40.0 kg/m² - You have responded to an antipsychotic medication (other than clozapine) in the past 5 years - You are medically and psychiatrically stable **You may NOT be eligible if...** - You have only responded to clozapine - Your BMI is outside the 18.0–40.0 range - You have serious medical conditions that would prevent safe exercise participation - You are not stable enough to participate in the study activities Talk to your doctor to see if this trial is right for you.