Saturday's Premier League clash against Nottingham Forest marks the Portuguese coach's one-year anniversary since replacing Erik ten Hag, and it arrives with United enjoying their best form under his management.
United have won three league matches in a row, a welcome turnaround after finishing 15th last season and losing the Europa League final, a period that left Amorim's future under serious threat.
Asked if he ever believed he might not reach a year in the job, the 40-year-old admitted: "It's hard to say, sometimes, yes. There were moments that were really difficult. Losing so many games was painful because this is Manchester United. We put everything into the Europa League, and when we didn't win, that was massive."
He added with a smile: "There were times I thought maybe it's not meant to be. But today it's the opposite. I know this was the best decision of my life, and I want to be here, but for that, I need to win against Nottingham."
Amorim, who has often spoken about the need for hard work and unity, said he takes pride in seeing his players "running and fighting for each other" as they prepare for their visit to the City Ground. United are hoping to end a run of three successive Premier League defeats to Forest.
The manager insisted he would not get carried away by their recent improvement, reminding supporters that the club are still rebuilding after what he previously described as a "storm" last December.
"We need to think positively but also be prepared, because football changes quickly," Amorim said. "We are not at the stage where I can say we will maintain our level no matter what. But I trust my players more now, and they trust me more. You can see that in how connected they are."
He continued: "It's about winning games. We are a better team now, we feel it and we know it. That belief helps us deal with difficult moments much better than before."
Amorim's side, now climbing back into the top half of the table, will be hoping to mark his anniversary with another victory, and a statement that Manchester United's long-awaited revival is truly under way.
Arsenal maintained their winning momentum in the Premier League after beating Burnley 2-0 away from home while Manchester United battled to a 2-2 draw at Nottingham Forest.
Arsenal are on a collision course with Crystal Palace over the scheduling of their Carabao Cup quarter-final, with Mikel Arteta insisting it would be "unfair" to move the tie.
Newcastle United head coach Eddie Howe has confirmed that new signing Yoane Wissa remains some distance away from making his debut for the club as he continues his recovery from a knee injury.
David Moyes has said Everton will be ready for the "raucous" atmosphere awaiting them at the Stadium of Light on Monday night, as they prepare to face newly-promoted Sunderland.
