The 36-year-old suffered a career-threatening Achilles injury against Tottenham in March.
Hreidarsson told The News: “When it happened at Spurs I felt a bit sorry for myself for about two hours. I’ve been lucky throughout my career with injuries, but at that moment I thought that had been my last game.
“It was a nasty injury to be fair, a career-ending injury, so it looked like the end. I definitely felt a bit sorry for myself.
“Then I thought ‘do you know what, it’s not going to end this way’. At that moment I decided I was going to do everything in my power to make sure I would be back out there and playing football again.
“The reward was so big to me just to make it back. Luckily it has gone right so far and now it’s a matter of getting a few more cobwebs out.
“It’s such a privilege playing football, I still have a lot of passion for the game and I will keep going until the legs fall off me.”