The 51-year-old former Papua New Guinea international was set to return home after his three-year tenure as Wigan head coach came to an end at the culmination of last season.
However, he was persuaded to stay in England by Centurions' new head of rugby Chris Chester, tasked with getting the club back into the Super League following relegation in 2021.
"I'd made the decision halfway through the year to go back to Australia but things change, the World Cup changed," Lam said at his first press conference on Thursday ahead of Sunday's opening Championship match against Whitehaven.
"The original intention was to finish off at Wigan and then go into the World Cup and then head back to Australia with a potential role in the NRL.
"When that all changed, I was heading back when Chris Chester rang me about staying here for 12 more months leading into the World Cup and I thought maybe I could do that.
"I was really excited from my conversations with the club and I've enjoyed every moment of my time here.
"It won't have any impact at all on my role with the Kangaroos. I'm in communication with Mal Meninga and the staff on a continuous basis through Zoom.
"They're relying on me, I guess, on having some answers to the COVID situation over here and the protocols on and off the field. And I guess I'm going to be finding exact places to train.
"I'm really looking forward to that. I am in a really good place at the moment and excited at being a part of this club."
Lam has taken charge of a new-look Leigh squad, with no fewer than 14 signings following a clear-out at the end of 2021.
However, with Joe Wardle and Jy Hitchcox injured in the friendly at St Helens last Friday and Edwin Pape yet to arrive from Australia, Lam will have just 18 players available for Sunday's game in which the Centurions will have 10 debutants.
