The defender moved to Forest on a free transfer after leaving Championship rivals Bolton Wanderers at the end of last season.
“When I first signed for Nottingham Forest, my dad told me about the history of the club and what a big club I was joining,” the 29-year-old told talkSPORT.
Mills has played for the some big clubs in England, such as Southampton, Manchester City and Bolton.
Forest is perhaps a different challenge for the defender, with the Reds stuck in the Championship for years and aiming to return to the Premier League.
Mills has scored four goals and created six chances in 18 Championship appearances for Forest so far this campaign.
The former Leicester City man has a pass accuracy of 64% and a shot accuracy of 53%, and has won 64 headers, one dribble and four tackles.
Forest are 15th in the Championship table at the moment with 28 points from 22 matches.
Dougie Freedman’s side are nine points behind sixth-placed Ipswich Town with a game in hand.