Mourinho was sacked by United in December 2018 after a two-and-a-half-year spell in which he guided the club to EFL Cup and Europa League triumphs.
The Portuguese returned to management on November 20, taking over at Tottenham just a day after Mauricio Pochettino was dismissed by the north London outfit.
He has masterminded three consecutive wins across all competitions since his appointment and takes his resurgent side to United in the Premier League on Wednesday.
Mourinho – who has returned to Old Trafford as a television pundit this season – looks back fondly on his time at the club but says his focus is now solely on Tottenham.
"This is a closed chapter for me," he told a media conference. "I left the club and took my time to process everything that happened.
"I took my time to prepare myself for the next challenge. Honestly, Manchester United for me now is in my book of experiences; it's in my history book.
"I feel good. I like to play big matches; I like to play against the best teams and that is the most important thing. Going back to Old Trafford is to go back to a place where I was happy. I can say that I was happy. I have a great relationship with Manchester United supporters.
"I went back as a pundit, which is a different perspective. I was really humbled by such a beautiful reception.
"On Wednesday, I go back as the coach of the team that is going is try to beat Manchester United and that maybe gives a different perspective."
Tottenham have confirmed goalkeepers Hugo Lloris and Michel Vorm remain out with elbow and calf injuries respectively, while Ben Davies (ankle) and Erik Lamela (hamstring) will also miss the trip to United.