Had an eye-opening conversation with a heart surgeon several years ago. This was 15 minutes after he completed surgery on my brother and riding partner. I told him that we rode 20-40 miles per ride several days per week and generally averaged about 20MPH with short sprints thrown in for good measure. He looked at me seriously and said, 'why do you ride so fast? You're not 35 anymore (we were both 55-56 at the time). Don't try to pretend you are.' That tends to sink in when you've been sitting in a hospital for hours waiting to hear if your brother survived his heart attack or not. I still ride, but at a slower pace. I've taken his 'everything in moderation' advice. Your mileage may vary
