Being "healthy" is not enough. I have had a couple friends about my age, both serious runners who took care of them selves. One simply keeled over from a heart attack. The other developed some sort a arythmeia that required surgery and while there an aortic aneurysm blew. Another guy, active swimmer and hiker and in really good shape found one of his coronary arteries badly backed and needed a stent. Worked well. All three would have passed for "healthy" and taking care of themselves and the ticker still went wonky.