With Zlatan Ibrahimovic ruled out for the season, Rashford has since been asked to lead United's attack.
The 19-year old proved he was able to do the job when he scored the winner from a free kick in United's first leg of their Europa League semi final with Celta Vigo.
After the match, Mourinho was quick to laud Rashford for his work ethic off the field and the England international admits he was chuffed to hear the praise from his manager.
"It's a massive thing when a manager like him says that," said Rashford.
"The best thing about it is that you've earned it. He didn't just come in and say 'there you go - play every game'. He's made us all work for his trust and respect.
"Sometimes it's difficult and sometimes it's easier but the players are all battling and improving to work for him. It's massive for us and you can see how everyone's come on this year."