Mourinho said he wanted to bury the past three years at Old Trafford, which saw David Moyes and then his own mentor Louis van Gaal struggle to emulate the title-studded success achieved by legendary manager Alex Ferguson.
"I feel great," Mourinho said in an interview filmed in London on Thursday and aired Friday on the club's television channel.
"It comes in the right moment in my career because Manchester United is one of these clubs where you need really to be prepared for it because it is what I used to call a giant club. Giant clubs must be for the best managers and I think I'm ready for it."
United officially appointed the former Chelsea, Real Madrid, Porto and Inter Milan boss on Friday after three days of contract negotiations. The 53-year-old Portuguese said he wanted to forget the lean years under Moyes and Van Gaal and think about the club's illustrious history.
The Red Devils have won 20 English league titles, 12 FA Cups, three European Cup/Champions League titles and the World Club Cup.
"We can look at our club now into two perspectives: one perspective is the past three years and another perspective is the club history," he said.
"I think I prefer to forget the past three years. I think I prefer to focus on the giant club I have in my hands now." Mourinho said his aim of winning top trophies at Old Trafford was realistic and pledged he would give everything he had to achieve it.
"What the players need to listen is: I want to win," he said. "I need the supporters and the players to feel I say that, but I think we can -- really."
He said he would "give what I have, and what I don't have -- so I will give absolutely everything to try and go in the direction we all want".
Mourinho said an "empathy" had built up between him and the club's fans over the years in which he brought opposing teams to Old Trafford.
"I think I know what they can give me. I think also they know what I can give them," he said. "I'm happy, I'm proud, I'm honoured, I'm everything."