King made the decision to retire from professional football five months ago at the age of 32.
England defender King battled a persistent knee injury throughout a career which saw him earn 21 international caps.
The ex-Spurs skipper told the Daily Mail that he had to admit defeat after years of managing the problem to make big matches.
He said: "I'll probably always think about what might have happened without the injuries.
"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 continues to work for Tottenham in an ambassadorial role, which also sees him get involved in community work organised by the club.