Jose Mourinho believes taking the Manchester United job means he is at the top of his managerial career, despite having been at some of the world's biggest clubs.
Two spells at Chelsea along with stints in charge of Real Madrid, Inter and Porto have seen the Portuguese win eight league titles and two Champions League crowns.
However, Mourinho feels the switch to Old Trafford is his biggest move yet as he prepares for his first competitive home match in charge when Southampton visit in the Premier League on Friday.
"I have been in some of the biggest clubs in the world," the 53-year-old told Sky Sports.
"This is like the top of my career, but it comes in the early stage of my career because as a manager I am really young, and I think I have the best years of my career to come up.
"I was not joking [when I say 15 more years] - 53 plus 15 is 68, so I would say 14, 15, 16 more years, but I don't see myself going home before 70."
Mourinho claims to have always enjoyed a positive bond with United supporters - even when in charge of opposing clubs - but looks forward to having them fully on his side in his new role.
He continued: "I've managed many, many times against Manchester United. I've enjoyed it. Even as an opponent I could create a good relationship with the fans, I never had problems, and I have not always behaved the best way.
"The first time I was running to celebrate a goal at touchline. Maybe it is Sir Alex Ferguson's doing, with the relationship we had, I always tried to be nice and have a relationship with the fans at Old Trafford.
"This time I go and for the first time I can do what I never did, which is ask for their support. I always play against them, and this time they are on my side.
"As a fan you can go to the stadium and watch the game, or you can go and play, and what I ask them to do is go to Old Trafford and play.
"If they play, it's 80,000 plus 11, versus 11, and the opposition has no chance. I give them that responsibility - if they are behind my players we have a big chance."