Amorim takes charge of United today, leaving Sporting top of the Primeira table.
After victory over Braga, he said on Sunday: "From tomorrow I will think about Manchester United.
"It's difficult to sum it all up right now. It's been an incredible adventure. I always felt like I was completely sure, but at many moments I had some doubts. Many people helped me.
"I lived in a very particular context, it was difficult when we arrived, but I know it will be difficult to reproduce what I have here elsewhere, then there are other places with different exposure and pressure, I did what I could, with stubbornness, but I always thought about the team."
Amorim added, "I can say with a clear conscience that the team has always been in first place. This time, apart from the mistake at the end of last season, this was the only time I thought about it... I had to do it. So, I regret this decision in the middle of the season, but I felt that it was my time and that we had to continue the best start ever and there is a lot to do."