The England and Manchester City defender, 31, made just 11 appearances in the Premier League last season after sustaining an injury to his foot and hamstring, and Stones has now admitted he thought about throwing in the towel altogether.
During an appearance on BBC Radio 5 Live, he said: "Last season was tough for me, to the point where I thought about stopping.
"I didn't want to do it. I had had enough of being so professional and trying to do everything right in my power, to then keep breaking down and not having the answers. It was a very difficult place to be in.
"There comes a point where you don't know why it happens and it is even harder when you put in so much effort, or you are ultra-professional, to be able to play and be available."
Stones added: "When that time comes and something happens, it would be easier to say 'well I didn't do X, Y and Z that's why' - but when you do it, it's then mentally challenging. Hopefully I don't go back to that place."
So far, Stones has made five appearances in the Premier League this season, and "deep down", the defender doesn’t think he would have gone through with his retirement.
He continued: "My emotions were high. I wasn't thinking straight. I don't think deep down I would have ever done it [retired].
"I said years ago when City wanted me to have a new challenge, I said 'I am going to fight'. That's all I have known since I was a kid - why should I stop that now?
"So yes, there is that fight in me and that winning mentality that doesn't want to stop."
Despite his injury, England manager Thomas Tuchel, 52, had asked Stones to join the Three Lions in Spain for training in June.
Stones said it was a "no-brainer" to join the squad.
He gushed: "My love for England, I think it's difficult to put into words. I love England so much - I love playing for England.
"I have had some of the best moments in my career playing for England [and at] tournaments. When he [Tuchel] said, 'Will I come out and be with the guys and continue my training', it was a no-brainer.
"I wanted to be there, be around the guys. He saw it from so many points of view. I hadn't been around the team [and] he knew that I was lonely training by myself, being in a difficult spot."
