Brad Thorn is as resilient as they come - in 16 years at the top level of rugby league and union he's never sustained a serious injury.

The worst has been a knee problem which required an arthroscope that kept the former Brisbane Bronco out of the NRL for three weeks in 1998.

But Thorn's immense love for the rugby codes, in particularly the All Blacks, has him fearful of what will come of his post-football life.

He expressed a vulnerability on Thursday in revealing he must be on guard against depression when he finally hangs up his boots.

"For me playing for the All Blacks is Christmas Day every week - I just love it, said Thorn, preparing for Saturday night's Bledisloe Cup clash at Etihad Stadium. "It concerns me afterwards because ... it's been a real big thing in my life.

"I've been doing it since I was six years old and I just love footy.

"It's quite daunting for me post footy. Obviously I'm going to do something else, it's going to be interesting. I have to keep an eye on it."

At 35, and in his second stint in union, the end is near in a remarkable career even though you wouldn't tell by the indestructible second-rower's form in his twilight years.

NZ-born, Brisbane-raised Thorn was given an early scare after the 2003 World Cup when he battled through a disappointing season in Christchurch before switching back to league.

"I got a little taste of it after 2004 but I was lucky I had an extra challenge which was the Broncos," he said.

"I hadn't made the All Blacks that year, I played out the NPC in New Zealand and I had a month or two off and I just stayed in NZ and was organising the house before going back to Australia.

"I felt, I have to be careful of the words I use, a little bit depressed because I spent all my life wanting to be an All Black and it was done, I was on the other side of my life.

"I felt a bit flat for a couple of months and then that challenge of the Broncos stimulated me again.

"That might be the key, having that challenge when all this stuff finishes so I can put my energies into something else."

A father of four and a strong Christian, Thorn is considering starting his own business or becoming a high school teacher but he has at least another year with the All Blacks.

The imposing 195cm, 114kg forward is a fixture in the All Blacks second-row and has been signed through to next year's World Cup when he'll be a few months off 37.

He's still keen to play on, possibly overseas, but has already talked to plenty of friends such as former Broncos teammates Petero Civoniceva and Shane Webcke about his next phase in life.

Thorn - who has won State of Origin matches, NRL premierships, Super 14 titles, Tri-Nations trophies and Bledisloe Cups - puts his longevity down to a strong body and good luck.

"Not having a serious injury in my career has been really big for me," he said. "At this age I can really enjoy my rugby.

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