The centre-back was forced to retire from the game in July after years of managing a series of knee injuries.
"I'll probably always think about what might have happened without the injuries," he told The Daily Mail.
The defender, now 32, made 21 appearances for England and featured at Euro 2004, but his international career finished abruptly when he tore a muscle in the opening game of World Cup 2010 in South Africa.
"It would have been nice to have had a run in a top tournament and shown what I could do for England," he recalled.
"One of the toughest things was that I wasn’t training and my muscles would keep breaking down: hamstring tears and groins.
"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.
"Too many times, after three or four games, I’d feel something and break down and have to start again. 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. Five minutes into the game I felt my groin go. I couldn’t actually face bringing myself off. I was embarrassed.
|POLAND V ENGLAND LATEST
|3/1||Poland are 3/1 with bet365 to claim victory over England
"So I struggled through to half-time. No-one really tested me. No-one ran me. It could have been one more run and I’d have been totally on the floor.
"I was just cheating out there, getting by. At half-time, they looked at it and there was clearly a tear. I was devastated."
King spent his entire career at Tottenham - captaining the side to victory in the League Cup in 2008 and a place in the Champions League in 2010 - and went on to describe how he continued so long despite his injuries.
"There was a lot of self-motivation involved, talking to myself," he commented.
"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.
"I knew my fitness levels were so low compared with those I was playing against. I had to trick myself into believing it wasn't about that.
"I'd tell myself, 'This is a football game, use your brains, use your intelligence'. That's the way I started to defend."
King was unable to train regularly and added that throughout his final seasons he never regained his former levels of fitness.
He continued: "There wasn't really any pain. It was more of a restriction. I couldn't bend the knee past 90 degrees and that would limit what I could do.
"I didn't like to go to ground because if my knee bent and jolted up that was really uncomfortable. I was never much of a diver-in but you just learn to survive. You find a way. You don't cheat, but you do what you can to survive.
"Some days it would feel OK and some days it would feel terrible. Some days I'd not train for the whole week and I'd go out the day before a game and it felt no good."