Any long football career needs a dose of luck and Harvey's body has given him some advantages.

But those close to the 38-year-old say a conscientious approach to his preparation and training has also helped set Harvey apart.

North Melbourne director of football Geoff Walsh said Harvey genuinely loves training, a desire that has enabled him to front up not only week after week but pre-season after pre-season.

"His enthusiasm just to turn up to training is quite obvious and it's enduring," Walsh said of Harvey, who is on track to play his record-breaking 427th game against St Kilda in round 19.

"It's probably why he's approaching the milestone of being the player who has played the most games in the history of the competition. It [his love of training] is rare."

Walsh said despite all his experience and all the praise bestowed on him, Harvey leaves very little to chance.

"He is obsessive with preparation, he's meticulous with routine," he said.

"I think the mental strength of doing something over and over again until you get it right, or until you get better at it is a real attribute that Brent has."

Walsh said dreams of another North Melbourne grand final win also helped keep the veteran coming back year after year.

Harvey was at North Melbourne in 1996 but only played in one game - and it wasn't the grand final - so 1999 remains his only premiership win.

Walsh said as a young man Harvey perhaps thought that at North Melbourne, playing and winning finals was par for the course.

But since then he has been in teams that have played in the finals and some that have missed out.

"The only [grand final win] he's played in, 1999, continues to drive him every year," Walsh said.

His mental strength is matched by physical strength and Harvey does have some natural advantages in that regard.

On a pound-to-pound ratio, where strength is measured against size, he is still among the six strongest players at North.

Roos high performance manager Steve Saunders said Harvey is endowed with fast-twitch muscle fibres, which are helpful in building strength.

Harvey runs 15 kilometres each game – a testament to his aerobic capacity – has hit speeds of 34 kilometres per hour during matches this season and is in the upper echelon of North sprinters.

Saunders said Harvey is well coordinated and built for speed, which has not diminished with age. He is also committed to gym work and is able to convert that training into on-ground strength.

LIttle about Harvey's training routine has changed in recent years because he knows how to look after himself, but staff encourage him to take a break every now and then.

AFL players are injury-prone, but Harvey has managed to spend 20 years in the competition relatively unscathed.

Saunders said all North players are put through musculoskeletal screening and Harvey has no obvious deficiencies that put him at risk and a lot working in his favour, including very stable joints.

But keeping a consistent training load has also been important in avoiding injury.