When she was asked, after her slalom gold and GS silver at the St. Moritz World Championships in February, what the limit was to her achievements, Shiffrin was tempted to poke fun: after all, when everyone thinks you’re bulletproof, the only way to manage it is with a little humor. “There is no limit,” she deadpanned in a mock-serious voice, then laughed at herself. She was being self-deprecating—but, it turned out, truthful. She continued: “I want to be the best skier. Not just the fastest skier, but the best, technically. I want to be the strongest person, and I want to be the most consistent, as well. And so far, my career has been like that. And I want to keep going with it.”

One reason none of these ambitions seem absurd is that, along with natural talent, she’s been striving to stay ahead of the game. Shiffrin is known as one of the hardest-working skiers, if not the hardest-working, on the World Cup circuit, someone who puts a remarkable amount of hours and sweat into her sport—and if you’re known for that among a pool of top-level athletes who aren’t exactly slouches, that says something. Physical training is one thing. Technique is another: in just the last couple of years, she’s noticeably improved everything from her turns to her timing. And she finally seems to be mastering the nerves that, she once told me, she sometimes felt as “these little, like, pellets that people are throwing at me. If I let one pellet hit me, then all the sudden the whole wad of them comes and I’m choking.” Shiffrin’s keen determination to keep developing her abilities, both physical and mental, is why she’s finally atop not only the slalom discipline, but the entire sport.

The World Cup overall title is just the latest jewel in Shiffrin’s crown, and larger and shinier than even her Olympics or World Championships gold medals. Since it’s the result of the accumulation of a whole season’s worth of points across every discipline, the title is a better measure of overall ability than a one-off race. And with more than 50 individual races on the calendar, it means a lot of chances to slip up. Or to show your stuff.

Her title makes Shiffrin a member of a club that includes the likes of Lindsey Vonn, Bode Miller and Tina Maze; she’s only the third American woman in history to win the overall after Vonn (2008, 2009, 2010, 2012) and Tamara McKinney (1983). That means people are already talking about goals that sounded nearly inconceivable just a couple of years ago: at some point, could she break the record to clinch the most World Cup victories in history? How many more overalls could she win? How many Olympic medals? What are her limits?

When she slalomed into the world’s living rooms during the 2014 Olympics in Sochi, it was the first time most of the world took notice of the then-18-year-old wunderkind from Colorado. Even though Shiffrin laughed about how all people seemed to remember of her run was her recovery—she was literally thrown by a change in the pitch, both skis sailing off the ground, only to get it together and grab gold—they had good reason. Her signature smooth rhythm and cool-as-a-cucumber approach was remarkable on a normal run; it was all the more memorable coming after a mistake like that.

Her performance spoke to her talent as a racer. But it also spoke to how a millisecond of mistake can change everything—which is why, no matter how impressive a skier seems, it’s always dangerous to make predictions. Shiffrin experienced this last season. After a scorching beginning to the 2015-16 season that included second place in her first race (a G.S. at Sölden) followed by back-to-back slalom victories in Aspen, she partially tore her MCL and had to sit out five races; she finished the season tied for 10th.

That’s why even Shiffrin’s biggest fan—her travel companion and mother Eileen—is wary of making predictions. Even minutes after Shiffrin’s second win at the World Championships in February, Eileen was still cautious. “With the overall, anything can happen,” she told me. “We saw that happen last year right up until the end. We never like to sell her competition short—ever, ever. Those girls are all bringing it every time they come.”

Eileen is right, of course. Though some top contenders, like Lara Gut and Lindsey Vonn, last year’s first- and second-place finishers, were knocked out of contention this season with injuries, Shiffrin still had very stiff competition, right up through the Aspen G.S. race on Sunday. Take the Slovenian Stuhec, who has taken on the team’s mantle after Tina Maze’s recent retirement: In every one of the last eight speed events, Stuhec has been on the podium. Or Italian dynamo Sofia Goggia, who topped off a solid season with two victories in speed events in Crans-Montana, two in Korea and third-and second-place finishes in the finals in Aspen.

But when it came to the overall, no one could catch Shiffrin. Although there are parts of her victory that—as with any top athlete—came down to an ultimately uncontrollable mixture of talent, luck and health, there are plenty of concrete reasons, too. This season was the one in which many of the skills she’s been working hard to master—from race technique to calming nerves—finally came together.

The one thing everyone you talk to mentions is how hard Shiffrin works. As her head coach Mike Day, who has also coached greats like Ted Ligety and Bode Miller, put it to Powder: “She is easily the hardest worker out there, male or female. Especially on snow, she skis a greater volume than any other athlete I’ve ever worked with at any level. Truthfully, it’s inspiring.”

“I’ve never seen anyone be so focused,” said her manager and former World Cup racer Killian Albrecht.

Maybe that’s why, when he was asked on camera at St. Moritz what Mikaela’s “secret” is, Shiffrin’s father Ted seemed slightly taken aback. “It’s a lot of things,” he finally said, “but Mikaela has incredible dedication.”

That means an extraordinary number of hours on the slopes and insane physical training. On a more personal note, it also means that Mikaela—who has been nicknamed “Sir Naps-a-Lot”—will famously choose a pre-10 p.m. bedtime over a party. That was even true on days like this one, when she’d clinched a victory and didn’t have to race the next day.

“We don’t really party much,” her dad said, pointedly adding, when the announcer pushed him: “Look at Mikaela’s face. How much more of a celebration do you need?”

Shiffrin echoed the same sentiment at her press conference. “The first thing I’m thinking about is, yeah, it’s all going to be fun [at the medals ceremony],” she said, “and that’s great, but I can’t wait to get in bed and just stop talking to people. I’m sorry. But true!”

All that work (and sleep) has paid off. And if you can squint past the gleam of those gold medals to the nuts and bolts of Shiffrin’s skiing, you can see exactly how.

Back in 2014, I asked Shiffrin about the skills she was working on the most. “One of the things I’m working on is just arcing,” especially at the top of her turns, she told me. “Some of the other girls—they’re stronger, they have more mileage on their skis, and they just know how to arc turns that I don’t feel comfortable arcing. So I’m trying to force myself into positions where I’m uncomfortable and I’d normally slide my skis and try to make the turn—and just arc it instead. I think I’ll be able to get some time there.”

You can see what she’s talking about if you look at that Olympics run:

It’s a fantastic performance, with or without the recovery. But look at how, coming into the turn, like at 0:14 to 0:15, her skis point nearly horizontally across the hill before she throws them onto the other edge, aiming them at the next gate. The effect is more of a Z than an S pattern as she comes down the hill. You can see how this throws some snow off her skis—a sign of sliding or skidding. That’s less efficient than arcing a fluid, clean arc completely around each gate for a couple of reasons. One is the friction. Another the fact that the skis are built to slingshot, and for that to happen, they need to build up potential energy through a smooth turn.

Ted Ligety, arcing master, explains it best in the video below: “The perfect turn would be a turn where you don’t slide at all. You start arcing, and you’re actually on an arc with your skis, the base of your skis pointing completely up the hill. And you’re just pushing on your ski. As that ski goes out, you trust that it’s going to come around.”

Has she succeeded? Judge for yourself: compare her run in Sochi to this year at the World Alpine Ski Championships in St. Moritz.

Especially when she gets some distance from the camera, like at 0:34, 0:40 and again at 0:47, you can see how she’s making a near-perfect S shape down the slope. It all looks a lot more fluid and clean. And remember: that’s an improvement on the reigning Olympic gold-winning slalom. In this sport, even the best have to be constantly getting better to stay at the top.

Shiffrin’s improved performance in disciplines outside of slalom was also key to her win this year: With so much competition on the circuit, it is very, very tough to win an overall without performing solidly in at least a couple of disciplines. And that’s easier said than done. Although it’s easy for a non-racer to lump everything together as “skiing fast”, the events are all very different, requiring different equipment, skills, strategy and mindsets; slalom is the most technical and turny. GS, short for giant slalom, is still a technical discipline, but the turns are bigger and the speed is faster than slalom, and it’s not uncommon for someone who’s amazing at one to struggle in the other.

Not too long ago, that was Shiffrin. “I’m at the point in slalom where, when I win, I have a pretty solid lead, which is comforting for me,” Shiffrin said in 2014. “But GS, I’m not at that point. I’m not at the point where I’ve even won a GS yet. So I’m trying to fix that all and just—I want to win a GS. I want to win a couple of GSes.”

Two weeks later, she did, nabbing her first victory in GS at Sölden. But she wouldn’t manage another victory for the rest of the season. Or the season after that.

Then came this year. Shiffrin kicked it off with a second-place finish in the season opener in the GS at Sölden. Then she went one better: she pulled off back-to-back GS victories in Semmering, Austria. Then a silver at the Championships in St. Moritz. In fact, of the 10 GS races she’s run this season, yesterday’s sixth place equalled her worst finish all year. That’s an incredible improvement.

Much of the change has been nailing the timing of GS. A slalom star like Shiffrin thrives on the fast-paced, quick-footed turns of the sport’s most technical discipline; as soon as you come around one gate, the next is already on you. GS is different.

“GS has been challenging for me because it’s harder to get that timing,” she said in 2014. “I feel like in slalom, it’s easy to get the timing, because there is no time. You just switch from edge to edge. But in GS, there’s a little bit more of a transition. There’s more time in between gates. I’ve always kind of found myself twiddling my thumbs a little bit in between gates. Trying to figure out when I need to start a new turn. And I’m starting to get that timing better.”

Since then, she’s figured it out. Want to see the difference? Look at her run at Sölden in October 2013:

She’s calm, collected and clean—all classic Shiffrin. But watch where she starts her turns. At 0:38, for example, she’s switching from one edge to the other a little more than halfway between the two gates. That means her skis aren’t pointing in the direction of the new turn until she’s pretty much at the gate.

Now look at her performance at Semmering this year. She starts to make a turn around 0:52. At 0:53, you can see where she’s switching her edges—just above the halfway point between the two gates. Which means that her skis are already pointing nearly across the hill, in the direction she wants to go, when she’s still well above the gate.

When you’re talking about a discipline won in the hundredths of seconds, the extra sliver of time that set-up carves out—multiplied by each of the 50-something gates—makes a significant difference.

So when Shiffrin put these things together in her GS this year, she was thrilled. After her second GS run at the Championships—she took silver—she was beaming. “I’m excited! Can you tell!?” she said. “I always knew I could ski fast GS, but it’s taken a while to actually put that out there. And this season winning my second and then my third World Cup [GS], and then coming here with a silver medal—I feel like I’m getting the consistency and experience is coming. So I’m really happy with that.”

Shiffrin had told me that, once she felt she’d gotten her feet under her with GS, she’d move into speed disciplines. Despite advice from all-arounder Tina Maze not to spread herself thin (“Don’t do every event, ever...It’s too tiring.”) that’s exactly what she’s done. She nailed a fourth place in the super-G in Cortina d’Ampezzo this January after three other races that didn’t see her crack the top 10, following it up with 13th in the Crans-Montana super-G and seventh in the super-G portion of the alpine combined (a strange elixir of an event that joins a slalom and a super-G race). And she had a respectable showing in downhill, the wildest event of them all, in her first-ever World Cup races in that event: She finished 18th and 13th at Lake Louise in December.

There are ingredients to a successful season that go beyond technical skills. One of the least quantifiable and most important might be a racer’s confidence. Shiffrin is no wallflower. But with so much riding on her career from such a young age (born to two ski racers, and winning her first FIS-level race at age 15), it’s no wonder she’s battled nerves in the past.

“Pretty much every single run in any race ever, I’m scared to death,” she told me in 2014. “I make sure I go to the bathroom before the race, I cover all my bases there, preparing to be like, horror-movie scared to death.”

On the course is her “Mikaela-bashing time,” she joked. “I’m constantly saying stuff like, ‘Crap, you just screwed up that turn, why’d you do that. Ah, you’re so slow’ ... Sometimes I’m like, ‘Just get to the finish, at least! ... At least do something right!’ And maybe that energizes me. But throughout the process, I’m scared of what I’m going to say to myself in my head.”

As pressure has built—and success has followed—that tension hasn’t completely gone away. “Some days are really good and some days I just feel like somebody’s choking me,” she said after winning the slalom in the Championships in February. “Today I had moments where I felt great and moments where I felt just like, no chance.” She’d slept terribly the night before. But after a solid first run, she attacked in the second. “That was one of the moments where I was like, yeah: finally I handled that pressure really the way that I want.”

Her outlook before that second run is especially telling. From the starting gate, she said, she could hear when Swiss star Wendy Holdener went through the finish. “I heard the crowd cheering so loud. And it was like, ‘Yeah, well, she has a medal. For sure. It’s probably gold right now.’ And I was thinking, ‘Oh, that’s cool. She must be happy. But today’s my day—not yours!’ And that was the last thought that went through my head.”

Here’s how Shiffrin made it her day:

On Sunday, after posing with her crystal globe for her World Cup overall title, Shiffrin said she couldn’t wait to go home.

“I think everybody’s tired,” she said. “I definitely feel it. It’s just about managing everything coming into the end of the year. It’s been amazing to race World Cup Finals in Aspen, in my home state, but it’s also a lot more effort being the American girl. Everybody is so excited, which is amazing, but I feel the need to take a little bit more time for everybody. It ends up being a little bit more tiring.”

The work never ends; she said the first thing she has to do when she gets home is to clean her room.

Can Shiffrin keep coupling her talent, technique and hard work with the kick of serious confidence that will get her onto the podium? Can she keep improving against competition that’s only ever going to get better? As ever, it’s tough to make predictions—and now that she’s a contender across all of the disciplines, she’ll need to be careful not to overextend herself. But it seems reasonable to say that Shiffrin, 22 and almost bulletproof, will be the one to watch going into next year’s Olympics. And it seems obvious to say that, at least right now, there’s no one in her way.