Earlier this season, the 24-year-old noticed a decline in his career, as he struggled to score and create as he did before.
The squad held meetings to address their poor league form, but Foden felt something was off as his body didn't feel the same.
"I feel frustrated I didn't get out what I wanted to get out of it," he told the Manchester Evening News in an exclusive interview.
"The position I was put in on the left was very difficult to influence the game.
"Coming off last season being the best player in the Premier League and playing centre-midfield, I do feel the position was quite difficult to get used to.
“I’m one who can play multiple positions and had to try to deal with it the best I could. I don't feel like England ever get going or performed to our potential."
"It was a challenging moment," he added.
"I've been playing since the age of five pushing myself every day to be the best I can. It's just the way I am, I've always given 100 per cent in training but when you add up all the game and all the travelling it is a lot for the body.
"I just wasn't feeling 100 per cent when I was training, and then there were a few niggles. There were times when I was getting frustrated a lot because I enjoy my football and want to be out there and when things are not helping you to be 100 per cent it's really difficult to accept that.
"For me, football is played with the brain and when the brain is mentally fatigued you're not going to see a player for who he is. I'm normally itching to get back but when I came back my body and my mental state was low.
"I had a bit of rest, just to give my body time to recover. I took the start of the season very slowly, I didn't play much and I was just resting and trying to get back to myself.
"My body just didn't feel how I was used to and it's something that I've had to deal with. I feel that's the reason why I had a slow start to the season.
"When you start the season good, I feel you have the rest of the season good but I missed periods at the start of the season so I think that's why it's taken me so long to get going. You can't dwell on it too much, these things happen to footballers and I've slowly been getting back to myself."