@doctorboo1 I am glad that you were finally diagnosed at 79 and are working hard to regain lost fitness. I was fortunate that in my later 50's my primary care doctor heard a heart murmur for the first time, and I was referred to a cardiologist who knew much about HCM. Camzyos was still in trial and Myqorzo was yet to become a publicly known drug in 2022. That's when I had a septal myectomy at Mayo at almost-76. I suspect that regaining fitness is similar whenever we have been away from any exercising, hiking, bike riding, running and the many other good workouts that are important for our health. I strongly suggest consulting with your doctor for an OK and guidelines for intensity. Have you considered working with a trainer? Ask your doctor about cardio rehab. While the fitness level of your 30's will probably never be achieved, you are doing a very positive thing to live your best life.