Man United are in a good position following their 1-0 victory over Celta Vigo in the Europa League semi-final last week and a win in the second leg will guarantee them a spot in the final.
The Portuguese boss has also put an emphasis on winning the competition as he rested key players who had played too many games in April in a vital Premier League fixture against Arsenal.
Speaking about the team, Herrera insists he’s found stability and balance under Mourinho.
“The previous seasons here I was happy, but with Mourinho I have found the balance and stability,” Herrera said. “He gave me a lot of importance from the beginning of the season. I feel I always have his support. That helps you perform better when you have your manager behind you.
“It is not only me. Everyone in the team feels the support of the manager.
“The only way is to try and win every game. You cannot select games. Every game is important. We are defending Manchester United, we are defending the greatest club in England, one of the greatest in the world. No excuses. Fight for every game.
“We have a lot of injuries at the moment, but we have players coming back. Sometimes in the difficult moments, you find the spirit and everyone works in the same way and pushes together.
“There are players who are not playing every week, but they can help us. We have a very good squad.
“All our focus is on the Champions League. If we get it, it will be a very good season.”
Last season many were aware of Herrera’s talent, but he just couldn’t get a run of games under Louis van Gaal.
He’s definitely been one of our most important players this season and it just goes to show the difference in how a player reacts after being valued by a coach of Mourinho’s standard.