Mourinho spent two and a half years as boss of United and won the Europa League and League Cup trophies in 2017.
Rashford was looking to establish himself on the side at the time, after breaking into the first team at the end of Louis van Gaal’s time in charge.
And even though his relationship with Mourinho often seemed difficult, he insists that it was a union that will prove good for his career.
“It was difficult, but I think when you think about it in five or six years, these are the moments that give you that mental stamina,” Rashford told the UTD podcast.
“As a versatile player, I have improved a lot and it largely depends on those two years under Jose.
“We have experienced ups and downs. Come to think of it, it was a difficult period but certainly a period that made me a better player. “
Mourinho brought Zlatan Ibrahimovic to Old Trafford during his first summer at the club, to find him after the couple were together at Inter Milan.
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And Rashford says the Swede was another figure he learned.
“His mentality was beyond anything I had played with before,” he said.
“He didn’t care what someone said to him or what anyone said about him.
“In terms of mentality, he was the key to my development, especially when Jose was there because he was someone who had already played under him and he knew you had to be some type of way to survive under him . “