Jim Fixx:

Author of the best selling "Complete Book of Running," which started the
jogging craze of the 1970s.

How he died: A heart attack....while jogging

Fixx was visiting Greensboro, Vermont when he walked out of his house and
began jogging. He'd only gone a short distance when he had a massive
coronary. His autopsy revealed that one of his coronary arteries was 99%
clogged, another was 80% obstructed, and a third was 70% blocked....and
that Fixx had had three other attacks in the weeks prior to his death.