Jose Mourinho claimed the sight of Tottenham losing to Sheffield United due to a lack of desire "destroys me a little bit on the inside". (More Football News)
Spurs took four points from games with Manchester United and West Ham in their opening matches after the Premier League returned last month, but a 3-1 defeat at Bramall Lane this week left them ninth in the table and nine points off the top four.
After the match, Mourinho accused his players of mentally giving up after seeing a Harry Kane goal ruled out by VAR in controversial circumstances, with Lucas Moura penalised for handball in the build-up after being tripped by an opposing defender.
Speaking ahead of Sunday's game against Everton, the Spurs boss again highlighted his concerns about his players' mental fortitude.
"[From a] desire point of view, they put more in than us," he said of the loss to the Blades.
"That disturbs me. That destroys me a little bit on the inside because the last thing in football is when you feel you should do more.
"It's not a problem for me to lose because of a goalkeeper mistake or a striker missed two goals or mistakes. It's a problem for me when I feel we could do more."
When asked what will fix any perceived problems in Spurs' mindset, Mourinho replied: "Time. Only time.
"One of the most difficult things in football is exactly that: to change mentalities. It's to change the state of mind. It's to change the team's soul. It's one of the most difficult things in football.
"Sometimes, you have incredible luck to have a majority of players adapted to these needs, and some other times you have incredible players but the psychological profile is different or was built in a different direction. So, only time can do it. You have a recent example of the new champions and you know what the process to build the team is."
Mourinho also ruled out targeting specifically older players in the transfer market in order to strengthen the mentality of the group.
"In this moment, I'm not going in this direction and I don't think personalities have to do with age," he said. "There are young people with incredible mentality and there are people with a lot of experience without the right mentality. So, I don't think it's about age; it's more about a certain profile."
Dele Alli has sustained a hamstring problem but Mourinho says the injury is "nothing important" and hopes to have the midfielder available.
