England's World Cup players learned to open up about their feelings to their team-mates in group therapy sessions, says Billy Vunipola.
The back-row has revealed how there were "handbags thrown" when the squad exchanged candid views during training camps that took place in the build-up to the tournament in Japan - intended to help heal the wounds from their 2015 exit.
Four years ago England crashed out of the World Cup they were hosting at the group stage following successive defeats to Wales and Australia, plunging Twickenham into crisis.
Eddie Jones was appointed head coach in response, and tasked psychologist Corinne Reid to run group therapy sessions.
"It's really hard but it is a thing - men don't know how to talk about their feelings," said Vunipola. "It took us a while but we got there in the end."
He added: "Eddie has definitely got the baggage out. It was something that was very important to us and it has probably freed us up a lot in terms of our relationships.
"Everything that we felt or thought, we just put it out to the group. There were a few bumps in the road but like anything in the world - with your family and things like that - there are always mishaps.
"It helps to listen to each other and caring about another person's opinion and taking it on board, rather than going back to your room and having a little moan to your mate.
"I think this is the first team that is willing to go deeper than saying 'I think you should have hit this ruck.' We have got down to it - and it has been good.
"You know Eddie will always look for things to improve us and that was probably the biggest thing we needed to improve - how together we can be.
"Every other team says they are doing it, but being brutally honest can hurt a few feelings.
"Being within the confines of England rugby, a lot of us are very precious. When you're at your club, you're the main man, but when you're with England you're just the next person.
"There were a few handbags thrown around but it was really good. She (Corinne Reid) gave us the platform to do it."
Vunipola is the only player to have started all four warm-up Tests and the victories over Tonga and USA and the Saracens number eight, who sustained three broken arms in 2018, is enjoying the workload.
"This is probably the best shape I have been in for the last two years so to not take advantage of that would be terrible for me," he said.
"I don't go into contact as hard if I am worrying about being wrapped up in cotton wool."