Sir Alex Ferguson admits he is in the "penalty shoot-out" of his managerial career.
Ferguson, 67, has made it clear many times he soon realised plans to retire at 60 were a mistake - and although he acknowledges even he cannot go on forever, the Scot is well aware he will find it difficult to adjust when he is no longer involved.
"I am scared about thinking about retirement. I have been on the train for so long that when I get off it, I am scared my body will shut down," he told L'Equipe magazine.
"Three reasons are going to make me say 'quit' - if my health deteriorates; if I no longer enjoy working; if I no longer have the strength to rise to the challenges.
"Each summer I ask myself these three questions. I go to see my doctor, to start off with. My age has put me on alert since I had a pacemaker set up four or five years ago."
Ferguson favours a footballing analogy to describe his situation.
"Today, I am at the penalty shoot-out stage of my managerial career," he said. "I am conscious of that.
"My doctor says, 'Boss, you are 67, your back is going to get worse and worse. There are mornings when getting up is not going to be easy'. These are the penalties."
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