My father died of his first and only heart attack when he was 66. He was of normal weight and exercised lightly (swam 2-3x/week for 15 minutes). He had atherosclerosis which was never diagnosed despite efforts to get medical attention. My mother wanted him to go to the Mayo Clinic, but he refused.
I have had a long journey to fitness, with a life long commitment to becoming fit meeting with some success and a considerable way to go. I read the article and commented upon it in the NY Times. While the heart may benefit from some strenuous exercise, I doubt that my other body parts would concur. At 58, I am 5'11" and 245lbs, down from 350lbs. I play tennis or racquetball 3-4x/week for 60-90 miinutes, do one other cardio machine 1x/week for 25 minutes, strength training 2x/week for about 30 minutes and stretching/core strengthening about 30 minutes daily. My body feels as good as it ever has in my life. In addition, I have made dietary changes, meditate most days of the week for 25 minutes, and have increased my sleep from 5 to 7 + hours/night. My anxiety level is as low as it been for as long as I can remember.
The reasons I have for avoiding excessive strenuous activity have to do with preventing injury and fatigue. I need to work 4 days/week so I pay attention to my body and push myself to a moderate to high level of intensity, but not very high so that I have energy for the rest of my day. My goals are not professional or olympic in nature, so I go for balance rather than extremes.