Mavididi left the Gunners last summer for Juve.
"The way he goes about his business was incredible for me to watch," Mavididi told BBC Sport. "How he applies himself every day in the gym and on the pitch. How he looks after his body, his diet - mainly off-the-pitch stuff. Everyone knows what he can do on the pitch, but off the pitch is what keeps him going."
And Ronaldo is one of the players with whom Mavididi has struck up a friendship.
"It is a really close-knit group, everyone is cool and there is good vibes, good banter," he says.
"I get on with most of them, Uncle Blaise [Matuidi] and obviously Ronaldo. He tries to give English banter but it is not that good - he is a good guy, very down to earth.
"The club make you feel really involved - it is a credit to everyone in the dressing room."