Root addressed the squad before training after admitting he was "hacked off" by Brydon Carse becoming the latest England player involved in a late-night drinking incident.
Carse was dropped for the Test after being briefly arrested during a night out in Derby on Saturday. Footage of the 31-year-old in handcuffs appeared on social media and the Cricket Regulator is investigating.
"It was a chat that was needed, a very good chat from Rooty," Tongue said. "He was very clear on the message of what it is like to be an England cricketer.
"He was honest with us all in the changing room. He said it straight. As soon as that chat was finished, our focus was fully on these next five days."
The incident follows a series of controversies involving England players, including Harry Brook's altercation with a nightclub bouncer in Wellington, Ben Duckett appearing drunk during the Ashes and Ben Stokes and Gus Atkinson being stood down after breaking a team curfew.
Tongue was present during the Wellington incident but was not disciplined. He said he had since tried to put it behind him and concentrate on cricket.
England won the first Test by an innings and 103 runs at Headingley. Victory at Lord's would secure a 2-0 series lead and England's first multi-match series win since 2024.
Tongue has also been in contact with incoming coach Stephen Fleming, who takes charge from the December tour of South Africa.
"He messaged me the day before the Test, touching on The Hundred and congratulating me on that," Tongue said.