Jose Mourinho says Roma called him just hours after he was sacked by Tottenham and feels he has been "misled" by previous managerial projects.
Mourinho is set to return to Serie A 11 years after winning the treble with Inter Milan in the 2009/10 season.
He was dismissed by Spurs in April after a disappointing run of results and caught most off-guard when he was announced as Roma's new manager in early May, beginning his new role next season.
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The 58-year-old says Roma, who finished last season in seventh, were very keen to have him.
"They really wanted me," Mourinho told GQ Portugal.
"It was almost instantly, me leaving Tottenham in the morning and Roma calling me in the afternoon. They wanted me a lot and were objective.
"Something I had already felt throughout my years in Italy was the Italian passion when it comes to football, specifically around Roma, a club that has won no trophies in 20 years.
These are new owners, who have a very humble approach in a way that they recognised this was a new chapter in their amazing professional lives, a chapter in which they needed help from someone with a broad experience.
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Although Mourinho is one of the most decorated managers in club football, his stints at Manchester United and Tottenham both ended badly.
Without naming specific clubs, the 58-year-old feels he has been mis-sold managerial projects before and that Roma will be different.
He added: "I make mistakes sometimes, I haven't always chosen the right project, or I may have been misled about the path of some projects.
"I've made mistakes or I've been led in a dishonest way into accepting what I shouldn't have, but in the end it's all the same.
"These aren't my words, they were said by someone who was much more important than me: Whoever has goals and drive, will never grow older.
"I still can't believe that I have 30 years of experience in professional football, or that I am 58 years old, because I am always renewing my motivation.
Lately I've been having very different projects to before. I went to Manchester United in a phrase of transition, not to say decay. I went to Tottenham who don't have a history of success. Now I go to Roma with new owners, but I immediately felt this empathy with the owners, the director and they straight away reignited the fire and passion I have for my job.
"So here I go on another Mission: Impossible. I say impossible because people tend to look at me and in their eyes there's only one way to measure success, which is that I have to win.
"I always say that if I were to come to Portugal to coach Belenenses or Gil Vicente, if I didn't win, then I wouldn't call it a success."
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