Erik ten Hag said he was warned off taking on the "impossible job" of Manchester United manager but admitted he could not resist the challenge at Old Trafford.
The Dutchman, who left Ajax to take over at United in 2022, ended the club's six-year trophy drought last season but has been under intense pressure in his second campaign.
United beat Chelsea 2-1 at home on Wednesday, easing the pressure on their beleaguered boss, but have lost 10 out of their 22 games this season in all competitions.
Ten Hag told fanzine "United We Stand" that he was advised how tough it would be to revive the fortunes of the 20-time English champions, who have been in the shadow of Manchester City for a decade.
"Everyone was telling me 'You can't succeed in that job'," said the 53-year-old. "They said it was impossible. Me? I wanted the challenge."
United beat Newcastle in the League Cup final in February and finished third in the Premier League in 2022/23.
But this season they are already out of the League Cup, trail Premier League leaders Arsenal by nine points and face an embarrassing group-stage exit from the Champions League.
Since Alex Ferguson retired in 2013, six managers have tried and failed to take United back to the top of English football -- David Moyes, Louis van Gaal, Jose Mourinho, Ole Gunnar Solskjaer and Ralf Rangnick.
"I knew it wouldn't be easy, but it was such a great club with such a great fanbase," said Ten Hag.
"People love Man Utd, or they are against Man Utd. I like clubs like this. Ajax was like this."
The Dutchman said earlier this week he was confident that he retains the backing of the United players after reports of rifts within the dressing room.
United are expected to announce that British billionaire Jim Ratcliffe is buying a 25 percent stake in the club in the coming days but the deal may not make a major impact on spending in the January transfer window.
"I don't think we will spend a lot," said Ten Hag.
"As a club, you have to look for improvements, so if you can find better and it's realistic financially and with financial fair play, the club has to go with it.
"But most of the time you don't attract the best players in the winter."
