Despite the success he has been criticised for the club's inconsistent spells over the last two seasons. The Portuguese manager said he knew that building United back into an European powerhouse would take time.
"I knew the club I was coming to," he told Sky Sports News. "I know that one thing is to go to a club that is prepared to win and you just need to arrive and give the last touches...
"I knew that was not the case (at United). The owners knew that. The CEO, he knew that. So when the question was, in this period of my career, am I ready for this kind of job? Yes, I am ready because my career was about new things all the time.
"So when I came in this period to United I was ready for this and I knew it was not to come and have simultaneous success. But, in spite of it, three trophies, three finals, probably a third or fourth in worst case scenario. Not bad."
In his second season, United are in contention to win the FA Cup, where they face Chelsea in the final. They are second in the league standings behind confirmed champions Manchester City and host rivals Arsenal at Old Trafford on Sunday.
(Reporting by Aditi Prakash in Bengaluru; editing by Sudipto Ganguly)
