
Steve was dying and didn't know it. He was racing cars and was exposed to lots of asbestos.
Another interesting factoid about Steve McQueen:
After Charles Manson incited the murder of five people, including McQueen's friends Sharon Tate and Jay Sebring at Tate's home on August 9, 1969, it was reported McQueen was a potential target of the killers. According to his first wife, McQueen began carrying a handgun at all times in public, including at Sebring's funeral. Two months after the murders police found a hit list with McQueen's name on it, a result of McQueen's company having rejected a Manson screenplay. In 2011, it was revealed that Sebring had invited McQueen to the party at Tate's house on the night of the murders. According to McQueen, he had invited a girlfriend to come along, she instead suggested an intimate night at home, which probably saved his life.