Johnson has been out with an abdominal injury for a year.
The midfielder admits he is looking forward to playing regularly again at the highest level.
“It felt like I was injured for a lot longer than a year because there were so many times when I thought I was close and then the injury would flare up again,” Johnson told the Sunday Mirror.
“There was never any point when I felt it was over for me. I’d get down about my situation sometimes, but I always knew it was only a matter of time before I’d be back.
“It can be tough to keep going, especially when you think you’re there and then you suffer another setback.
“Then you pick yourself up, motivate yourself to go in the next day and start all over again.
“I’m a lot tougher mentally now than I was before the injury – because I’ve had to be.
“I’m probably still another few months away from getting back into the physical shape I was in before the injury.
“I reckon it will be another eight or 10 games before I’ll really be knocking on the door of the first team.”
