The mixed martial arts star never takes a step back, always looking for an edge, be it working with elite gymnasts or sprinters.
But St-Pierre's biggest strength is also his biggest weakness.
"I'm completely obsessed," he said of the way he approaches each fight.
When a grain of doubt enters his mind, the beast in the gym becomes brittle.
And on Friday, a shopping list of distractions finally took their toll on one of Canada's most famous athletes.
Citing the pressures of being champion and of being in a constant limelight, St-Pierre said his life has become "completely insane" and a "freaking zoo."
Admitting he was no longer up for the rigours of fighting in a cage, the UFC's pay-per-view king vacated his welterweight title and announced a hiatus from the sport.
St-Pierre (25-2) also cited personal issues, which he declined to detail. But clearly they have obscured his obsessive focus in a sport whose athletes spend months preparing for fights.
"Physically I'm 100 per cent, I'm still young, I'm on top of the world," the 32-year-old from Montreal told a media conference call. "But mentally I just feel like I cannot go through another training camp right now and I don't know when I will be able to."
UFC president Dana White said No. 1 contender Johny (Bigg Rigg) Hendricks will fight No. 3 (Ruthless) Robbie Lawler for the title on March 15 in Dallas.
"I think this is the right move for Georges St-Pierre," said White. "You can hear by listening to him he's got a lot of issues personally that he needs to deal with."
St-Pierre had cast doubt about his future last month following UFC 167, a controversial split decision win over Hendricks, when he said he needed time away from the sport to sort out some personal issues.
That enraged White, who did not like the idea of one of his biggest assets walking away — especially in the aftermath of a controversial decision.
But White calmed down after talking to St-Pierre later that night. And on Friday, he continued to downplay the drama.
"At the end of the day, it's really not that big of a deal. The guy's got some things that he needs to deal with. He was classy enough to say 'I'm not going to jam up the 170-pound division while I deal with these things, I'm going to step aside and handle myself and then I'll be back.'"
In the wake of the Hendricks fight, a TMZ report said the champion was dealing with a family illness and a personal issue. White later told The Canadian Press that St-Pierre had told him the report was not true.
St-Pierre loosened up during Friday's call, joking with reporters that they were not going to get anything personal from him.
"I'm going to take a break. I need this," he said Friday. "I need to have a normal life for a bit. I'll feel better and come back stronger."
Having a normal life was a theme repeated throughout the conference call.
Asked what he wants to get away from, St-Pierre said he loves his sport.
"As much as I choose to do it, now I choose to not do it."
He said he expects to be back, although he sounded far from certain.
"I don't know when, I don't know if, I think I will (be back) I can't say 100 per cent. But right now I just don't want people thinking about me."
Press tours, cameras and trash-talking were some of the things he said he needed to avoid.
St-Pierre was somewhat vague about a comeback.
"I believe one day I will come back. The problem is I don't know how long (I will be away)."
He said he has already conquered Everest three times before, when he lost to Matt Hughes (in 2004) and Matt (The Terror) Serra (in 2007) and when he came back (in 2012) from knee surgery.
"And if I have to do a fourth time, believe me, I feel like I'm, going to do it."
White, who explained GSP's UFC contract was considered frozen, said he believed St-Pierre will be back.
St-Pierre exits ranked second to light-heavyweight champion Jon (Bones) Jones in the UFC's pound-for-pound rankings.
White called St-Pierre "the greatest welterweight ever" and "the gold standard in everything."
"And as far as working with us, there's nobody better. If I had 475 guys like Georges St-Pierre, my life would be a lot easier."
A gentleman outside the cage who shares little of his personal life, St-Pierre has always taken his responsibilities seriously.
In 2008, he missed an interview session with a visiting reporter who was left standing outside a Montreal gym. His manager at the time advised that St-Pierre had suffered a minor injury earlier in the day and had forgotten about his interview with the reporter.
The journalist told the manager not to worry, given they had already had a previously scheduled appointment for the next day.
St-Pierre, however, had a different idea.
He drove to the gym to collect the reporter and took him out for dinner to do the interview. Then he drove the reporter to his hotel, apologizing again for having been late.
While other fighters wore T-shirts and sweats, St-Pierre — taking a page from some champion boxers — always wore a suit for his post-fight news conferences.
St-Pierre, who said he will keep training, has no need to fight again. He has made millions and made a point of looking after his family when the cheques started coming in. One of his first duties as champion was to pay off the mortgages of his parents and sisters.
The UFC is wasting no time getting round to the post-GSP era.
Carlos Condit is currently ranked No. 2 among welterweight contenders but he has lost to both St-Pierre and Hendricks. And White noted that Lawler just beat Canadian contender and GSP training partner Rory (Ares) MacDonald.
"Not to mention the fact that there's not doubt that the Robbie Lawler-Johny Hendricks fight is going to be an absolute gunfight."
White said Condit may also be on the Dallas card. Condit was previously due to fight Matt (The Immortal) Brown until Brown was sidelined by a back injury.
As champion, St-Pierre has worn a target on his back since he first won the title in 2006.
"The situation I'm at, it's a lot of pressure," he said. "It's like every fight I'm carrying weight on my shoulder. Every fight, it's like you add weight on your shoulder. Every fight.
"At one point it comes so heavy that I have a hard time carrying it myself."
St-Pierre has survived turmoil throughout his career. He lost his championship belt in his first title defence before winning it back. And he has endured a string of injuries, including knee reconstruction surgery in December 2011.
That prompted the UFC to pit Condit against Nick Diaz for the interim title. Condit won but was beaten by St-Pierre when the champion returned to action at UFC 154 in November 2012.
St-Pierre was the first Canadian to hold a UFC title since Carlos (Ronin) Newton, who held the welterweight crown for seven months in 2001 before losing it to Matt Hughes.
St-Pierre lost to Hughes, now a member of the UFC Hall of Fame, in a title bout at UFC 50 in 2004 but won the rematch at UFC 65 in November 2006 to claim the championship belt.
His initial reign at champion was short-lived. Beset by family illness and lacking focus, GSP was upset by Matt (The Terror) Serra in his first title defence at UFC 69 in April 2007.
GSP fights as he prepares. A good camp equals a good performance. He paid a heavy price for a bad one.
St-Pierre retooled, changing his management and revamping his coaching staff.
"I truly believe that this loss is probably the best thing that ever happened to me,'' he said at the time.
At the suggestion of a sports psychologist, he carried a brick around with Serra's name inscribed on it. Then he threw it in the chilly waters of Montreal's South Shore to bury the memory of the Serra loss.
St-Pierre has not lost since.
He won his title back from Serra three fights later in commanding fashion, at UFC 83 in Montreal in April 2008.
The decision over Hendricks was a record 19th win in the UFC for St-Pierre, moving him past Hughes at 18. It also extended his string of victories to 12, the longest current run in the UFC.
The Hendricks victory also moved GSP past former middleweight champion Anderson Silva for most wins in UFC title bouts at 12.
St-Pierre holds the record for career fight time in the UFC at five hours 28 minutes 12 seconds.
He also owns the UFC mark for most championship rounds fought (52). UFC 167 was St-Pierre's 14th championship fight, one behind Randy Couture.
St-Pierre also leads the UFC records in total strikes landed, significant strikes landed, takedowns landed and takedown accuracy rate, according to FightMetric.
"I'm content," he said of his legacy.
St-Pierre is not the first UFC champion to give up their title.
Tim Sylvia voluntarily gave up the heavyweight championship belt in 2003 when he tested positive for steroids, which was a pre-emptive strike to being stripped.
Bas Rutten gave up his heavyweight title in 1999 to campaign as a light-heavyweight. Injuries forced him to retire soon after.
Frank Shamrock voluntarily vacated his title in 1999 and retired, although he later returned to action outside the UFC.
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