Michael Johnson has revealed that he has been receiving treatment for "mental health" problems over the last few years.
The 24-year-old broke into the Manchester City team at the age of 18 and had been tipped to go on to represent England at senior level.
However, yesterday he was released from his contract with the Premier League champions, having not featured for them since 2009 because of a spate of injuries and problems off the pitch.
Reflecting on the club's decision, Johnson told the Manchester Evening News that he would not be looking to join another team.
"I am more disappointed than anyone but that's the way it goes," said Johnson. "I have been attending the Priory Clinic for a number of years now with regard to my mental health and would be grateful if I could now be left alone to live the rest of my life.
"It's a terrible shame. It's hard to accept when your career ends early and for his to end at his age will be really difficult to take."
Johnson spent part of last season on loan with Leicester City.