Speaking with PBS's Charlie Rose, Ferguson said he no longer got "worked up" over United's results.
"I'm not interested in managing again or getting myself worked up about Manchester United's results," he said.
"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 to the Kentucky Derby and the US Masters, the Melbourne Cup. I want to visit vineyards in Tuscany and France."
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