A SOUND MIND IN A SOUND BODY: The short and long-term effects of aerobic, strength, or mixed exercise programs on schizophrenia symptomatology. “We concluded that 3 weekly sessions of a moderate to vigorous progressive exercise program for 16 weeks improved the symptomatology of individuals with schizophrenia in all three groups, with no differences between them. However, the effects had declined to baseline levels by the 10-month follow-up, suggesting that exercise interventions should be maintained over time.”

Yes, exercise stops working if you stop doing it.