Rashford had played under Mourinho from the beginning of the 2016-17 season until the removal of the Portugese coach in December 2018.
With Mourinho, Rashford was able to add Carabao Cup and Europa League tournament wins in his kitty.
"It was tough but I think when you look back on it in five or six years, they're the moments that give you that mental toughness. As an all-round player I've improved a lot and a lot of it is down to those two years under Jose," official website of Manchester United quoted Rashford as saying.
"We had ups and downs. When I look back at it, it was a tough period but definitely a period that made me a better player," he added.
Rashford has a total of 19 goals in 31 appearances across all competitions to his name for United in 2019-20 before being sidelined due to a back fracture earlier this year.
Under current manager, Ole Gunnar Solskjaer, Rashford has flourished and has scored 19 goals in all competitions this season.
Rashford was sidelined due to a back fracture earlier this year.
The 22-year-old was expected to be out for three months, but Manchester United manager Ole Gunnar Solskjaer clarified that it was unclear whether Rashford would be making his return before the end of this season.
Currently, all sporting action across the world has come to a halt due to the coronavirus pandemic.
( With inputs from ANI )