"If you are going to be a sportsman you have to show the right sort of passion," he said.
"It can get a bit stroppy at times but as Vince Lombardi said; 'if winning isn't everything, why do they keep score?"'
As his kids extend their sporting repertoire, Marshall is branching out this season, penning a column for the Herald while he continues to work as an analyst for Sky television during the Super rugby season, ITM Cup matches and the All Black test schedule.
That new chapter began for Marshall in 2010 when he quit playing after 17 years of first-class rugby. He did not want to stop but an offer to join Sky was a golden chance and would allow his young family to settle back home after their gypsy lifestyle in Europe.
During his All Black career Marshall often jousted with the media and never thought he would join the fourth estate. But when he dipped his toes into the broadcasting world in Europe with some work for the BBC and Sky UK, his viewpoint softened. Not his opinions or his ideas though, which made him such an attractive target for Sky.
Marshall began his All Black career in '93 as the sport and administrators eased themselves towards the inevitable pay for play stakes two years later. Many struggled to cope with that transition and the lifestyles afforded by the huge pay rises.
The halfback was determined to make the most out of his sporting talents, he did not want to mix that with study or an apprenticeship which he felt would inhibit his focus.
"I needed to put all my time into rugby, that was my livelihood and I felt my talent only came out when I worked hard. My teammates used to call me the sneaky trainer because I felt a halfback had to be fitter than anyone and I worked hard at that and all the other areas like my passing game."
When Marshall became a senior All Black he earned very good money. He was determined to use his skills to claim that income stream for as long as he could here and then offshore.
Top rugby took him from some unruly teenage times into a more disciplined life and significant rewards.
"The game was a life-changing experience for me. When I saw where the game could take me if I worked hard at it and put my mind to it, it took me away from the things that were distracting me and I saw the rewards that my talents could bring if I put the work in."
When Marshall moved from his Mataura origins to Christchurch, he was inspired by age-group contemporaries such as George Gregan, Rod Kafer, Andrew Mehrtens, Jonah Lomu and Jeff Wilson to shoot for the All Black altar. Marshall began a building apprenticeship but gave that away when he reached the early stages of his test rugby target.
"When I got that first taste of All Black rugby I just wanted more and knew I'd have to work even harder to stay there so I put all my time and effort into that," he said.
Marshall struggled to ditch all of his unruly behaviour but worked hard to direct most of that competitiveness into his rugby where he took it as a personal affront if others were pitched as his rival.
"Whether it was conducive to me being healthy around team environments, it probably wasn't, but people knew I was competitive and coaches knew I was that way," he said.
"I've met a few All Blacks who were young when I was coming to the end of my career and they said I could have made more of an effort. But the way I looked at it, they were young and I was hanging on as well and wanted to stay there.
"I was focused on what I was trying to do at the other end of my career and when they wanted their shoulders rubbed and their egos stroked, I could have done with the same thing."
Marshall's competitive fire stoked his career when he went through some choppy chapters. His passion was one of the weapons in his locker.
A card school involving Sean Fitzpatrick, Zinzan Brooke, Marshall and Jeff Wilson would have shown that sparky confrontation in all its glory. Brooke and Marshall were regular roomies who indulged in dawn 'til dusk competitions.
Brooke would speed sign his autograph on jerseys, balls and posters and pile the merchandise on his teammates as he motored through a session. Resting in his room, he would challenge Marshall to hit something in the fruit bowl on top of the television without their head leaving the pillow.
"I got taught by the master, whatever skills I have in competitiveness, they were well drilled into me by Mr Miyagi, Zinzan Brooke," Marshall said.
He carries that attitude about improvement into his Sky work.
At first he felt awkward commenting on old rivals, teammates or his coaches. However Marshall has made a point of discussing trends, laws and styles in the game with them all so he is in tune with the latest ideas.
"That is very important to me. I talked to Steve Hansen on the last tour because I want to be consistent about what I am doing yet have strong comments and observations of substance.
"I am still an apprentice at Sky, still learning and I seek feedback from everywhere including the public, who were only too willing to give me advice when I was a player, and I work hard at it all the time.
"I formulate opinions and try to make it constructive whether it is criticism or not. It is not the Bible, it is an opinion. People who take it as fact and call me an idiot and much worse, they miss the point. I make comments and open up avenues for others to voice their thoughts on your views."
Working in television gave Marshall the opportunity to retire.
He played his last game against Leicester in front of 80,000 at Twickenham and when his team lost, he wanted to put the wrongs to right in the following year.
He signed a one-year deal with Saracens but Sky were keen for him to join their team and Marshall knew it was time.
"The game keeps evolving and testing us and making us think and for me that is the fascination. There have been a few 'oh bugger' moments, times when you are overreactive but you go with your gut instincts. Replays can show you up and I'm learning to go with that too.
"We all get things wrong. If there is a perfect person out there I'd like to meet them."
Marshall remembers one match he was doing from the sideline when he blurted out about the two Aarons before his mind went blank on Cruden and Smith. Or the superb test in Johannesburg last year when Bryan Habana took off and Marshall said the try was inevitable before Beauden Barrett rounded him up.
"I thought here is one of the great wings, he's intercepted or whatever he'd done and had to score but Barrett got him just and made me look stupid," he said.
In his off-season, Marshall watches a variety of sport to extend his range of views, expand his vocabulary and learn about other commentators' timing and delivery. "I'm open to ideas and think that the more concise and direct you can be is better. It's tough in the heat of the moment but I love still being involved in the game I love. It is a job and I want to work hard at it and continue to learn just as I did when I was playing."
