[Extremely Extreme Extremist]

It's the Jimmy Fixx paradox. Guy was a legendary runner in the 70s and even wrote a book about it. All he did was run.

Then keeled over from a massive heart attack.

[Fred Hayek]

Jim Fixx had genetics working against him. Read further, you will find that he outlived his brothers by quite a bit. Running got him some extra years. There was family history of heart problems involved.