They’ve come too far, for far too long, to mess it all up now.

And so the eight members of the Canadian men’s curling team are spending the three weeks before the Winter Olympics sequestered in a rental home in Vancouver. They train only when the rink nearby is empty and otherwise pass the time shooting pool, sitting in a hot tub and thinking about their families back home.

“It’s like a frat house without the booze,” said Marc Kennedy, a 2010 gold medalist and an alternate on this year’s team, who is dealing with the disappointment of missing one of his daughters’ dance recitals. “Everybody here has pretty wonderful spouses.”

As thousands of Olympians worldwide collectively hurtle through the final weeks of preparation for the 2022 Games in Beijing, they are integrating a new exercise into their daily regimens:

Sidestepping Covid-19, by whatever means necessary.

With the Feb. 4 opening ceremony in their sights, athletes are cutting off contact with loved ones, changing the very ways they train and, in many cases, ceasing all activities outside the realms of competition. The task has felt increasingly herculean amid a global surge in coronavirus cases inflamed by the highly contagious Omicron variant.

The emotional toll of all this, of living in fear of getting sick, of thoroughly disrupting their lives to avoid it, has been as taxing as their hardest workouts. But the alternative — contracting the coronavirus, being forced to sit out the Games and, in effect, erasing years of preparation and anticipation for this singular moment in their careers — is simply too devastating to ponder.

“Everyone is testing positive right now, and that freaks me out,” said Emily Sweeney, 28, a luger from Portland, Maine. “I keep thinking of all the crappy situations I got through to get to this point, and it just feels like such a big risk just to be existing in this world right now.”

Avoiding Covid-19 had of course been a goal for athletes from the start of the pandemic; getting sick is at odds for people whose livelihoods depend on their physical well-being.

But at this point the concerns of Olympians — young, fit and vaccinated, as a whole — are less about the illness or any symptoms and more about the testing regimen. Athletes traveling to the Games must produce two negative results in the days before they fly to Beijing, and everyone on the ground there will be screened each day.

Positive tests could keep athletes from boarding their flights to Beijing or force them into an isolation period of indefinite length once there, rendering all their hard work, all their suffering and sacrifice, essentially meaningless. It is no surprise, then, that some Olympians have been plagued by feelings of helplessness, a sense that at any point their dreams could be dashed before they even begin.

“We are playing Russian roulette every single day,” said Brittany Bowe, an American speedskater. “You can take all the precautions, wash your hands, wear a mask, and somehow you can still get Covid. In my opinion it is luck of the draw at this point.”

Anxious about the unknown, athletes have taken fate into their own hands. They have shrunk their lives into streams of socially distanced training sessions and an unending blur of deep nasal swabs.

The snowboarder Maddie Mastro estimated that she had not seen her family or friends, besides her boyfriend, since November. Like other athletes interviewed for this article, Mastro said she long ago stopped dining out and had been wearing a mask at all times whenever she was away from home.

Nathan Chen, the top men’s figure skater in the United States, has been regularly spotted wearing masks during full-speed practice sessions on the ice before these Games.

The Australian figure skater Kailani Craine, nervous about pulling her mask down for even a moment, has been reluctant to eat even on lengthy flights this season, lest she make herself the slightest bit more vulnerable to infection, according to her coach, Tiffany Chin.

Maame Biney, an American short-track skater, had planned to go out and celebrate with her family and close friends after securing her place on the team — before thinking better of it at the last minute.

“I was like, ‘No wait, if I get Covid, then I’m not going, and that’s not fair to me or my teammates to risk that,’” she said. “And so I told them, ‘Hey guys, I just need to stay super safe, and I can’t go outside, so we can have a FaceTime celebration.”

Her teammate, Kristen Santos, on top of double-masking at all times, has put her fiancé “on lockdown” this month, limiting his movements to minimize her risk of contracting a case.

“He went for groceries at 10 p.m. the other day,” Santos said.

In Europe, members of the American biathlon team have been operating in “roommate pods” while bouncing from training camps to events: Their roommates are the only people they can eat with or generally be around without a mask.

“It’s certainly shaping every aspect of our day-to-day lives, because it would be a major, major bummer to miss out on four years — a lifetime really — of hard work for a careless moment,” said Susan Dunklee, a biathlete heading to her third consecutive Olympics, who has been craving things as simple as going out for coffee on a day off. “Sometimes you do go crazy in your hotel room.”

Covid anxieties have even reshaped the way teams train.

For instance, the four men competing in the team pursuit event for the U.S. speedskating team, the current world-record holders, are limiting the amount of time they actually practice together — the event requires skaters to come into physical contact — to reduce the risk of getting the virus.

Similarly, Joel Johnson, the coach of the American women’s ice hockey team, said he was struggling to strike a balance between taking precautions and arranging sufficient training time for his players. For now, producing negative tests was occupying more brain space than planning for the Games.

“Covid worries us more than anything,” said Johnson, who has been holding team meetings virtually. “We’re not worried about any opponent, whether it’s Canada or Finland or Russia or Switzerland or anybody. Right now, we’re worried about how do we get there and how do we get there prepared to play?”

The risks of athletes congregating in one place became clear this month at the U.S. figure skating championships, where eight people — three individual skaters, one pairs team, one ice dance team and one coach — withdrew from the event after testing positive for Covid.

In other sports, athletes are skipping competitions that might normally serve as final dress rehearsals for the Olympics. An unusually high number of top athletes — a group that included the American snowboarders Shaun White and Chloe Kim and the Chinese skier Eileen Gu — elected to skip the X Games this weekend in Aspen, Colo.

“That was a calculation a lot of people had to make,” said Gus Kenworthy, a British freestyle skier and two-time Olympic medalist who is attending the X Games. He was wiped out for several days after contracting the coronavirus in October.

The effect of all this — isolating before entering further isolation in Beijing — has placed a heavy mental burden on athletes.

Jessica Bartley, director of mental health services for Team USA, said she and her colleagues had heard from countless Olympians struggling with the uncertainty of the moment. Bartley and her team have doled out guidance, and tangible steps big and small, to help put the Olympians’ minds at ease.

“I think it feels like it’s a little more in your control if you have these things to do,” she said.

And so athletes are mustering up their last bits of discipline and determination to navigate these final, perilous days before the Olympics. There is one last kick in the race to the Games, and no one wants to stumble now.

“Now is not the time to loosen up on that stuff,” Mastro said. “Now’s the time to tighten up on it.”

Jonathan Abrams, John Branch, Scott Cacciola, Alan Blinder and Kevin Draper contributed reporting.

Top photographs by Daniel Kopatsch/Getty Images (Sweeney); Jurij Kodrun/Getty Images (Dunklee); and Rick Bowmer/Associated Press (Bowe).