Ferguson is already the most successful manager in the history of the English game, having won 20 major trophies in his time at Old Trafford.
But he is already beginning to ponder life after football, saying: "You have to think about time for yourself.
"I think my wife deserves a bit of my time, too.
"The older you get, the more you feel guilty about it.
"My wife, Cathy, was the one who talked me out of retiring last time but she wouldn't do that now.''
But Ferguson, who has been United manager for more than 21 years, insists he has no immediate plans to step down.
"I know I would find it hard to give up managing United,'' he said. "I can't do it, not at the moment anyway.''