Conditions like high blood pressure, high cholesterol, diabetes and some mental health conditions often cause few or no symptoms, even when they are causing harm in the background. The medicine keeps them controlled, which is exactly why you feel well, so feeling fine is a reason to continue, not to stop.
If you stop a maintenance medicine, the underlying condition can come back or worsen, sometimes silently until it causes a serious event such as a stroke, heart problem or relapse. The lack of symptoms can give a false sense that the medicine is no longer needed.
If you feel so well that you question whether you still need the medicine, raise it with your doctor rather than stopping. They can review your condition, run any needed checks, and decide together with you whether the treatment can safely be reduced or stopped.