At first, all she wanted to do was run a marathon. It didn't take long, though, for Jessie Diggins to realize she wasn't thinking big enough.

Her coach didn't want her racing on pavement, so he made her agree to one condition: she had to run the 26.2 miles along the Appalachian Trail. Intrigued by the challenge, Diggins chose a demanding route that carried her over four mountain peaks in Vermont. For nearly seven hours, she ran nonstop, hurdling fallen trees and high-stepping over rocks and roots.

"At the end of it, I was like, 'Wow,' " Diggins said, still feeling the rush two years later. "I have so much appreciation for my body and what it can do. What it feels like to be strong as a woman and an athlete, to be able to run up and over mountains. It was such an empowering feeling."

That helps explain why Diggins, of Afton, is not intimidated by the fact that no American woman has ever won an Olympic medal in cross-country skiing. That long stretch of futility doesn't mean it's impossible, just extremely difficult — kind of like running a marathon in the mountains. Having conquered one of those ambitions with no problem, Diggins believes there is no reason she can't handle the other at the Pyeongchang Winter Games.

Diggins, 26, enters her second Olympics as a more seasoned and technically sound skier. The biggest transformation has happened in her head. With four world championships medals and a long list of historic achievements, she knows she belongs in the cross-country conversation with the dominant Norwegians and Finns and Swedes.

"Jessie is at the point now when she gets up to the starting line in almost any race, she thinks, 'I could win this,' " said Kris Hansen, who coached Diggins at Stillwater High School and still trains with her in the summer. "Four years ago, the idea of making the podium was still like, 'Well, maybe, if everything goes perfectly.' That is a huge change for her. She's done with that starry-eyed, just-happy-to-be-there phase."

Diggins' first race is at 1:15 a.m. Saturday (Minnesota time) in the 7.5 km skiathlon.

At the 2014 Olympics in Sochi, Russia, Diggins learned firsthand how elusive the Olympic podium can be. When the U.S. failed to live up to its hype and came away empty-handed, she doubled down on her preparation for Pyeongchang.

She's already shown she can go farther than anyone expected. When her coaches looked over her Appalachian marathon course, they checked her math — and discovered she had actually run 30 miles.

"Having four world championships medals gives me this boost, thinking, 'You know, I've done this a couple of times,' " said Diggins, who is third in the World Cup overall standings. "It's not a shot in the dark. It's not, 'Maybe in my wildest dreams, this could happen.' Nope. I've done this, and I know what it takes.

"Is that a guarantee that a medal is going to happen? No. But I'm working my absolute hardest, and I've done it before. Going into these Games, I know it's possible."

Embracing the 'pain cave'

It wasn't the Vermont mountains, but Afton's River Road was as close as Diggins could get during her summer break in Minnesota. For that matter, it wasn't much of a break, either.

The grind of elite cross-country ski racing requires as much discipline and rigor in warm weather as it does when the snow falls. Once a week in the offseason, whether she's training in Minnesota or with her team in Vermont, Diggins supplements her workouts with something extreme: maybe a 20-mile run, or a 3½-hour session of roller skiing. Or her gut-busting climbs on roller skis up the daunting grade of the River Road.

"It's the steepest hill in Afton, about as high as Afton Alps," Hansen said. "She will roller-ski up that hill for 4½ minutes, absolutely as hard as she can. And then she'll turn around and ski down so she can climb it again. She'll do that 10 times, even though she's just about ready to collapse. Her work ethic just amazes me."

“I'd say in 60 percent of my races, I am not fully conscious at the finish line. I've had people come and unclip my skis, and I couldn't tell you who it was because I was so out of it. And I'm proud of that.”
Jessie Diggins

That seemingly bottomless capacity to endure pain — even to welcome it — has distinguished Diggins since eighth grade. When she talks about blacking out at the finish line, or vomiting, or feeling as if her lungs are about to explode, her voice rises with excitement and her eyes widen in wonder.

Diggins calls it the "pain cave," that point in every race where muscles scream and the mind goes dark. Her greatest fear, she says, isn't the agony that awaits. It's the idea that she might finish a race without that sensation, knowing she didn't wring every last drop of energy out of her body.

"I'd say in 60 percent of my races, I am not fully conscious at the finish line," Diggins said. "I've had people come and unclip my skis, and I couldn't tell you who it was because I was so out of it. And I'm proud of that.

"There is a certain joy in the fact that you're pushing your body to a new limit. You figure out how strong you are mentally when you find that wall and somehow push past it."

It's a quality that's essential on the World Cup circuit, where every athlete is swift and strong. As Diggins has ventured deeper into the pain cave since Sochi — "there's a lawn chair in the back, with my name on it," she joked — her results have reflected that commitment.

At last year's world championships in Lahti, Finland, she won a silver medal in the freestyle sprint and bronze in the classic team sprint with Sadie Bjornsen. Her four career medals at worlds — including a gold in 2013, in the freestyle team sprint with Kikkan Randall — are the most of any U.S. woman in history. Diggins and Randall became the first Americans to win a world championship in cross-country skiing, and in 2013, they were the first U.S. skiers to win a World Cup team event, in the freestyle team sprint.

This season, Diggins finished third overall in the multistage Tour de Ski, the first North American woman ever to make the podium in that event.

"I met Jessie when she was 15 or 16 years old," said Randall, who will ski in her fifth Olympics in Pyeongchang. "I saw this girl skiing with her ponytail flapping, and I thought, 'Wow. That girl has the right energy. She could be good.'

"Two or three years later, she was on the world championships team. She skied incredibly well, but she had to learn the ways of being on the road and the demands of competing in Europe. Now we're seeing it all pay off, and she's only 26. The best for her is yet to come."

The convivial competitor

During the 2015-16 season, Randall — the team's longtime standard-bearer — took the year off after having a baby. Diggins landed on World Cup podiums six times that season, yet she took pains to ensure she didn't monopolize the spotlight.

She's always been a ray of light in a sport that could quickly turn grim under the weight of its physical demands. The U.S. team's "glitter fairy" started a tradition of face-painting on race day several years ago to keep things light and fun. If there's a birthday, she's singing and baking muffins. If there's free time, she's organizing a bowling outing or convincing teammates to go sky diving or bungee jumping.

"Everyone on our team has a role, and Jessie is the bubbly, energetic, bring-everybody-up person," Bjornsen said. "She's the first one to celebrate with you, and she totally brings the good in the bad times."

In 2016, Diggins' gleeful antics went viral. She choreographed a dance routine to Bruno Mars' "Uptown Funk," taught it to the entire U.S. team, shot a video and saw it rack up more than a million views on the web.

"Coaches, techs, anyone who comes in my way, I will face-paint them all," Diggins said. "The glitter, for me, is a promise to honor the little girl who just wants to go super-speed. This is supposed to be fun. You don't ever want to lose that."

In her joyful orbit, no one is truly a rival. Anne Hart of Stillwater, now Diggins' teammate and roommate with the Stratton Mountain School T2 team in Vermont, laughs at the assumption that there was any edge to their epic teenage showdowns.

Hart lost to Diggins by .07 of a second at the 2010 Minnesota state high school championships, after a classic 5K considered the greatest Nordic race in state prep history. Diggins' generosity as a training partner — and her example of discipline and dedication — helped Hart to a breakthrough season this year, putting her on the Olympic team alongside her fellow Minnesotan.

Diggins often says she is at her best in team races, because she wants so badly to win for her teammates. Hart said it's impossible not to follow her lead.

"Jessie can dig deeper than anyone I know," said Hart, a graduate of St. Paul Academy. "She was born with that ability. But she also has the willingness, the desire to push herself to the point where she's blacking out during a race. She wants to be the best, and she's very determined."

Pursuing another summit

Diggins' success — and her personality — have elevated the profile of the U.S. women's cross-country team heading into the Pyeongchang Games. She is appearing in a national TV ad for Comcast, shot in Afton, and her dog, Leo, has joined her in an internet campaign for Milk-Bone. Diggins also has been featured in Shape and People magazines.

Despite her growing national and international fame, she remains very much a child of Minnesota. Diggins writes a blog for the Minnesota Youth Ski League website, donates her racing suits to young athletes and visits with Hansen's high school team. In November, she conducted a free clinic at Theodore Wirth Park, followed by a meet-and-greet in the chalet; more than 50 people joined her for an outdoor workout on a cold, drizzly night, and dozens more waited as long as 90 minutes to wish her well in Pyeongchang.

"In the youth ski league, even the little boys say she's their favorite," Hansen said. "Everyone knows Jessie. Everyone likes her. And everyone is going to be cheering for her at the Olympics."

Diggins knows what a medal would mean to cross-country skiing in America. Last summer, to prepare herself to plumb the darkest corners of the pain cave in Pyeongchang, she looked for a follow-up to her Appalachian adventure.

This time, she roller-skied for 100 kilometers. She came away thinking that if she could ski for 6½ consecutive hours, she could do anything. That includes getting the U.S. women to the Olympic mountaintop, a marathon journey 46 years in the making.

"The sport needs this," she said. "It needs someone other than the Scandinavians to be ranked in the top five or six in the world. To me, it feels like it's not a responsibility, but a privilege to help change the culture of skiing to 'Yes, we can.'

"We have another chance. And I'm gunning for it with all my heart."

rachel.blount@startribune.com