The Portuguese manager admits he was "overwhelmed" and at times too emotional as he navigated the challenges of a club enduring one of its bleakest periods in half a century.
He meets Everton on Monday, a fixture that coincides with the first anniversary of his debut match in charge - a 1-1 draw away at Ipswich.
Much has changed since then, with United now enjoying their longest unbeaten run under his leadership: five matches, including three victories, offering a welcome sense of momentum.
Amorim describes his opening 12 months as a "good year" overall, though last season's struggles were stark. United slumped to 15th in the Premier League, their lowest finish in 50 years, failed to qualify for Europe, and crashed out of the Carabao Cup in a humbling defeat to League Two Grimsby.
The manager concedes there were difficult days and sleepless nights as he grappled with the scale of the task.
This season has brought fresh shocks - notably poor performances against Grimsby and Brentford - but Amorim believes the team are at last moving in the right direction.
"It was a good year," he told MUTV. "I learn a lot. I change how I see things. I learn for the future and the present. Some days were really hard, some nights were really hard but then I had some moments I really enjoyed.
"This is a massive club and I would not change for any club. When you belong to this club, you belong to something really special. We are here to stay, I hope. I think it was the best decision in my career [to come]."
"It was everything at the same time," he added. "I felt last year, I was always overwhelmed with the games. I didn't have the time to settle down, to understand that my job is not just the pitch, it's outside the pitch, [it] is to push for everyone.
"I felt like, last year, I was really emotional all the time, because I was struggling with the results.
"I'm always saying that this is going to take time, but I'm the guy that has the bigger responsibility to take care of everything and to control the emotions a little bit better."
