The Scotland midfielder, after leaving Manchester United last summer, finished the season as a Serie A champion and also Serie A Player of the Year.
McTominay told BBC Sport: "The people in Naples are incredible, they're passionate, and everywhere you go, there's someone shouting 'Forza Napoli'. They want to talk and have conversations, and that inspires you every time you step onto the pitch. Italy has a totally different lifestyle compared to England, from the way they eat to the way they live.
"It's given me a lot of mental strength. I used to live close to my family, now I'm 2,000 kilometers away and I can't see my mum, my sister, or my kids whenever I want. But sometimes you have to step out of your comfort zone, and I've always been proud of that."
De Bruyne fantastic addition
Asked about Kevin de Bruyne's arrival from Manchester City, McTominay added: "He's an incredible player and obviously someone who will bring a lot of quality to the squad. Having someone like him in our squad is fantastic.
"Bringing players of this quality and nature into the squad is very, very important, and that's where we want to build on, without settling for what we have."