My grandfather rode regularly from around the age of 16 until the time of his death-- nearly 70 years in the saddle. He ended up needing a quad-bypass in his late 60s. On a pre-op trip to the cardiologist, the doctor said to him, "I've got good news and bad news. Good news is, you've got the heart of a 20 year old. Bad news is, you have the arteries of a corpse."
No amount of cardio will keep you in shape if you eat like a human garbage can, which he did. And I'm not judging, if anything I'm jealous. I ride and hike for over 200 combined miles a week, eat vegetables by the fistful and avoid high sugar foods. I'll be lucky if I live as long as he did.
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