In an interview with American TV station PBS, Ferguson addressed the possibility of returning to the Old Trafford dugout, should David Moyes leave in the near future.
"I'm not interested in managing again or getting myself worked up about Manchester United's results," Ferguson said.
"United are in good hands with David Moyes. He will be fine. He's a good manager.
"You would be throwing your money down the drain if you put any money on me coming back as a manager.
"I made my decision. The timing was perfect. There is no way back for me now. I've got a new life.
"I want to go the Kentucky Derby and the US Masters, the Melbourne Cup. I want to visit vineyards in Tuscany and France."
Ferguson also confirmed that Chelsea attempted to lure him to London in 2003.
He said: "They used an agent to approach me when Abramovich first took over the club, and I said no chance."
Ferguson also apparently confirmed that Wayne Rooney did ask to leave Manchester United at the end of last season, despite denials that he handed in a transfer request.