The 32-year-old announced in July he was hanging up his boots after years of fighting against a troublesome knee problem. King, who now works as an ambassador for Spurs, reckons he will always be left wondering how successful he could have been without the injury.
"I'll probably always think about what might have happened without the injuries," he told the Daily Mail.
"When my knee started coming up I was 25 or 26, and was starting to feel I had a good understanding of the game and my position and could go from strength to strength.
"I had to deal with the injury and do what I could to keep my career going. I'll look back and realise I gave it everything I could to try to perform but it was difficult."
King was capped 21 times by England and was part of Fabio Capello's squad at the 2010 World Cup in South Africa.
But injury struck early in the campaign and left King wishing he could have enjoyed a decent run in tournament football for his country.
He said: "Fabio Capello had wanted me to link up with England but I never felt fit enough. I wanted to put a long run of games together before I could even think about it.
"But before the end of that season, I played a run of games and my form was good. When he asked me if I wanted to go to the World Cup, I felt good. I felt the time was right.
"To break down again was a feeling that's hard to describe - it would have been nice to have had a run in a top tournament and shown what I could do for England."
Source: PA
Source: PA