Mick Fanning credits it as the reason he became a surfing world champion. Craig Fitzgibbon's certain it's why he's about to slip into a Kangaroos jumper again.

When Fitzgibbon ploughed through fitness drills with Australia's World Cup train-on squad in grand-final week, he looked at some of the talent beside him and thought: "Oh shit, I might be up against it."

Imagine the shock, then, when he heard his name on the car radio as Ricky Stuart's 24-man squad was announced on Tuesday morning. Fitzgibbon will credit the Roosters' renaissance ("I've just jumped off the back of our team") and the confidence of NSW coach Craig Bellamy and Country's Laurie Daley ("I owe it to them for giving me a start") but the rebirth can largely be ascribed to the man himself.

The changes began at the start of the year, when he started feeding off the lessons teammate Anthony Minichiello had been picking up from an unnamed trainer, who was helping the Roosters fullback recover from the back injury that has cruelled his past three seasons. Another shock call-up to the NSW side put him in contact with Fanning, who had been brought into this year's camp.

"I remember seeing him [Fanning] in an interview doing a certain type of training and I just asked him what it was," he says.

Corrective Holistic Exercise Kinesiology (CHEK) is a holistic training program created by Californian Paul Chek, and Fanning had used it after pulling his hamstring off the bone.

"It's not only his [Chek's] things," Fitzgibbon says. "It's drinking the right water, making sure we balance our diet. I eat organic food these days. All these little training exercises. Mini and I are bouncing off each other, seeing what's new. It's been exciting. [Dragons centre] Matty Cooper gets into it as well. At my age, you have to come up with things that keep tricking your mind and body into action.

"I changed the way I trained. Instead of a big run or a big boxing session or something like that, I'd get in the gym and do a lot of rehab and pre-hab. Just preventative exercises that strengthen up a lot of little areas of my body."

The transformation has been there for all to see this season. At the Australian team medical on Thursday, as he slipped the green-and-gold jumper onto a 31-year-old frame still not prepared to yield, the moment wasn't lost on Fitzgibbon.

"It felt pretty nice sliding back into it, I'll tell you," he laughs.

It must have seemed light years from when he was the only player sacrificed after Australia's 24-0 loss to New Zealand in the 2005 Tri-Nations final - something that stuck with Fitzgibbon because he thought he'd played reasonably well.

There and then, his representative career was apparently finished and it mirrored his subsequent life in clubland, where the captain limped from one-year contract to one-year contract as the Roosters fell from the heights that won them the premiership in 2002. Too many times since then have journalists written that he is a heartbeat away from retirement.

But this year, a rebirth.

The Roosters started winning under Brad Fittler. Then Fitzgibbon was spirited into the NSW side at the behest of Bellamy, who saw value in his mobility in the middle of the field.

"The last couple of years have been like bashing my head against a brick wall," Fitzgibbon says. "I lost rep jumpers and pay cuts and everything seemed to be heading downhill. When you're getting smashed around like that, it's a pretty unforgiving world, footy. I was doubting myself for a while there. It backed me into a corner, where I had to do something about it.

"It's not without hard work. I've altered a lot of things. In the last five or six years, I haven't finished a season where I could run. I could play tomorrow if I had to. That's rare for me. I can only put it down to all those changes that I've made."

Fitzgibbon is unclear of the role his former Roosters coach wants him to play during the World Cup. His experience will be a factor for a squad laden with back-rowers high in quality. He was more than prepared to cut short his off-season. But does his new holistic approach to training allow him to drink any alcohol?

"I still have plenty of time to let the rest of my hair down," he says. "I'm still drinking beer and I'm still having a good time. But when I used to do that, I used to eat whatever I wanted. That caught up with me."