The Spaniard arrived at Old Trafford earlier this month, but is yet to make a first-team appearance as compatriot David de Gea continues to impress.
Valdes had his first outing for the Under-21s on Monday, and coach Warren Joyce has spoken of how the keeper showed his team-mates a video beforehand.
The video told the story of veteran American athlete Dick Hoyt, who has pushed his quadriplegic son Rick in adapted wheelchairs while contesting in gruelling endurance events.
"The lads are in the room listening to this," said Joyce. "It was unbelievable.
"I was going to do something but Victor said '[Pep] Guardiola used to do this'.
"He's a very humble guy and a model professional."
'I won the World Cup and I said to myself, I've done it all, I need to keep feeling emotions': Raphael Varane opens up on why he had to leave 'indescribable' Real Madrid for Manchester United
'When I see Phil Foden play, he just seems like a shy lad - that holds him back a little bit. He has been tried in every position, but he just hasn’t performed': Ex-England star makes bold claim about Manchester City man
