Remember Jim Fixx?
Yeah.
From Wikipedia: "...Cooper concluded that Fixx was genetically predisposed (his father died of a heart attack aged 43 and Fixx himself had a congenitally enlarged heart) and several lifestyle issues (Fixx was a heavy smoker prior to beginning running aged 36, he had a stressful occupation, he had undergone a second divorce, and his weight before he took up running had ballooned to 220lbs)."
What that doesn't mention is diet. But I guess that nothing can guarantee good health.