That is exactly my story, too... the arrogance of youth and of the serious exerciser. In the long run, genetics is almost always more of a factor. In my case I also mistakenly believed that genetics was in my favor since my sedentary and overweight dad had never been diagnosed with a heart condition. I learnt that I was wrong about that, too, when he had his cancer scans... but by then it was too late for me. If I had been thinking about all this better I would have gone on a statin in my 40s to combat the rising cholesterol instead of waiting until my 60s.