Michael Vaughan said his first job after regaining the captaincy was to rally the beleaguered England team.
He admitted England were mentally low after their 5-0 drubbing in the Test series to Australia but they now have a one-day series to prepare for.
"I do expect that there will be a few mental frailties because of what's happened," said Vaughan.
"I inherit a very talented team, but there will be an effect from the 5-0 Ashes whitewash."
He added: "Anyone who says there won't will be lying."
England start their one-day quest with a Twenty20 International against Australia in Sydney on Tuesday and then embark on a triangular tournament also involving New Zealand.
"We have made mistakes and we're sorry for that, but this is a great challenge for us to try and pick ourselves up"
Vaughan, who captained England to their shock Ashes series win in 2005, said the players needed to accept they had played poorly in the Ashes and move on to the next challenge.
He even apologised for England's woeful Test performances.
"We won the Ashes in 2005 and collectively took all the praise, and we have to collectively take the criticism now," he said.
"We have made mistakes and we're sorry for that, but this is a great challenge for us to try and pick ourselves up.
"Mentally the players are going to be tested, because they will have been hurt and affected by the Ashes series. My job is to try and ensure that they're not affected that much."
He said he needed to get all-rounder Andrew Flintoff to rediscover his form with the bat and ball.
Duncan Fletcher admitted Flintoff had been burdened by the captaincy in Vaughan's absence.
"My challenge as a captain is to get Freddie (Flintoff) back to playing how he did a year or so ago, when we all saw him being a leader by the way he batted, bowled and fielded," said Vaughan.
"It's a great job but a tough job, being captain. He's done a remarkable job in my view under the circumstances, the pressure that he's been under."
Former England batsman Geoffrey Boycott told BBC's Sportsweek programme Vaughan was a great captain but doubts remain over his fitness.
"He's tactically sound, he's a strong-minded individual and I think he's very good and he will help," said Boycott.
"My only reservation is he's a kid who's had four operations on a knee, he is worried that if it goes again his career is finished.
"So he's got that on his mind of getting fit, getting some form with his batting and he's got to pick up a losing team that has lost so badly for the first time in 86 years. That's a big job."