Jose Mourinho believes Manchester United will be better prepared to challenge for "big things" next season but insists he has no problems with the squad he inherited from Louis van Gaal.
United held out for a 0-0 draw at Manchester City on Thursday, despite a late red card for Marouane Fellaini, and remain firmly in the hunt for Champions League qualification.
They will secure a return to Europe's premier competition irrespective of their domestic finish if they can claim Europa League glory, with the first leg of a semi-final at Celta Vigo on the agenda next week.
However, United have been distant from the Premier League title race and, even allowing for an ongoing 24-match unbeaten run in the top flight, Mourinho feels his players are short of resilience and belief.
"The group was a nice group, honestly. Good people, good boys – committed people," he said.
"I think Mr Van Gaal left here a good group of boys with very good relations.
"I think they miss happiness, they miss trust, they miss belief. They miss this extra bit that brings you resilience, brings you fight.
"When we meet again on July 9 for next season it will be a stronger group. The new players, when they arrive, will find a group more ready to go for big things.
"But the reality is that we are fighting to win the Europa League and we are fighting to finish fourth. So, let's go."
United will do so while grappling with an extensive injury list.
Top scorer Zlatan Ibrahimovic suffered a cruciate knee ligament injury against Anderlecht last week, as did Marcos Rojo in the same game, to join fellow defenders Chris Smalling (knee), Phil Jones (broken toe) and Timothy Fosu-Mensah (dislocated shoulder) on the sidelines.
Paul Pogba missed the Manchester derby due to a hamstring problem and he will remain out when Swansea City visit Old Trafford on Sunday, with Fellaini's ban further compromising Mourinho's midfield options.
Before facing City, Mourinho seemingly questioned Smalling and Jones' commitment due to them being unwilling to play through their injuries but he feels the collective ordeal could be character-building for his players.
"We arrive into an extreme situation where I think it must be unique in football – two cruciate ligaments in the same match," he said.
"In my career I had one [of my players suffer this injury] in 17 years and now against Anderlecht I have two in one match. We are very unlucky, that is the only thing I can say.
"Then the other injuries – the Pogba one, Antonio Valencia last week – are the injuries of fatigue, from an accumulation of matches. That is normal.
"Smalling and Jones were in the English national team, training.
"Maybe it is an opportunity to make the team mentally stronger. Maybe it is a blessing. So, let's see if they can come back."
Mourinho could be boosted by Juan Mata returning from a hernia operation ahead of schedule. The Spanish playmaker had been expected to miss the rest of the season.