What life changes must be made if you have hypertrophic cardiomyopathy?

Depends.... In most cases nothing. If you have significant obstruction to blood flow from the heart you may be asked to exercise to moderate levels only. Depending on the thickness of the septum, degree of obstruction, arrhythmias and family history your cardiologist may recommend a defibrillator which generally precludes high intensity sports. It all depends on the degree of severity of the condition.