Boateng, who now plays for Eintracht Frankfurt, was punished by the club as their form disintegrated towards the end of the 2014-15 season.

Both he and Sidney Sam were suspended indefinitely, with sporting director Horst Heldt saying "the level of trust is no longer there and we're not convinced that they can help us" amid allegations of a lack of commitment.

Boateng said he had considered quitting at the time and had "said to myself: Why not?"

He added: "I've earned a lot of money, seen everything and have a wonderful family. What else can I do? But that was only for two days."

The former AC Milan midfielder, 30, said his dream was to help young players, adding: "I want to play at a good level for as long as possible and just stay healthy.

"To win trophies? I've never been a trophy guy. I would love to win the Champions League one day, but I am being realistic that I now most likely won't win it. Fine with me.

"My dream is to help young players. I don't want them to make the mistakes I did in the past. The rest? I was 20 when I dreamt of other things.

"If I had always been honest to myself, I might play at Real Madrid."

Berlin-born midfielder Boateng also praised Frankfurt coach Niko Kovac, a former teammate at Hertha.

"He helped me take my first steps in professional football," he said. "Niko understood me -- he knew how to control that tiger."