Jim Fixx
From Wikipedia: "Fixx died at the age of 52 of a massive heart attack, after his daily run, on Route 15 in Hardwick, Vermont. The autopsy revealed that atherosclerosis had blocked one coronary artery 95%, a second 85%, and a third 50%. Some who opposed his beliefs said this was proof running was harmful.[2] However, Fixx came from a family where the men had poor health histories. His father suffered a heart attack at the age of 35 and died of one at 42. Given Fixx's unhealthy lifestyle until he took up running, many argued that running added many years to his life."