Chelsea's Cahill happy being fully fit for new season
Cahill has forgiven Belgium winger Dries Mertens for causing the injury which forced him out of Euro 2012 and set his sights on being part of England's 2014 World Cup qualification plans.
Now Cahill is back and featured in England's 2-1 win over Italy in Berne on Wednesday.
"Football is a rollercoaster. You finish the season winning the Champions League and then miss out on the Euros," he said.
"Missing the Euros was a nightmare. Emotionally it was frustrating when you hear the national anthem being played and you know you should be there.
"The injury was one of those things - but it was one of those things that could have been prevented.
"I don't think he (Mertens) meant it. It was a daft thing and I don't think he meant the outcome, but unfortunately that is what happened.
"You can't reverse it, so you get on with it and move forward. It was bad timing."