Hart's treatment by former West Ham manager David Moyes is a particular sore spot and the goalkeeper blames him to some extent for being left out of the England World Cup in Russia.
"Politically, it's been quite difficult to believe in me recently," Hart told the Daily Mail.
"I'm a big head to chop off if you want to shake things up. I've got vast experience and won things but I was a loanee, which is what you expect from someone around aged around 18 to 21.
"It was difficult for people to warm to what I was doing. Except from inside the dressing room, nobody knew what I was about. Wherever I've been then that's where my heart and soul is.
"I've got a few years here and want to go deep with it. I needed to cut ties with City and I feel like I've been set free. Officially, I've been at one club for 12 years. I'm excited to be at a new one. My whole life is this club."