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Mosi sits, swaying on an orange watercooler in the dark night. Ricky and Arylis are working out the knots in his calves and plotting what he needs to do to stay in the race. Mosi is so beat up from the heat that he looks more like a boxer than an ultrarunner.

Gravity has been his enemy through these hills, and it continues to work against him while he tries to stay upright, tries to keep his eyes open. But he's knackered. He needs sleep.

"Here," I say, posting up on the bumper of our rented Chevy Tahoe. Mosi leans against me, and I drape my arm next to his head as a pillow. He falls asleep.

If actions speak louder than words, then all you need to know is that I let that dude drool into my hand while he took a 10-minute nap. Eighty miles of sweaty back pressed against my lap while my ass went numb on the back bumper of that car.

If this isn't love, I don't know what is.

This love is not some sedentary, lazy noun. It's not an ephemeral feeling in the air, with little pink hearts floating around it. It's not steeped in pheromones and expressed with roses and kisses and candlelight.

Love is not something you believe in. It's a thing you do. Actively. Athletically. With gusto. Because love is a verb.

And I can tell you that everyone in this crew loves Mosi. You wouldn't be here if you didn't. It would be too passive to say, "There's a lot of love here." And like any good English teacher, I'm here to shun the passive voice.

I f---ing love that dude. It's real.

Because all I want in this moment is for him to succeed. At all costs. I have no needs bigger than Mosi. No drive for myself, no hunger, no pain, no exhaustion. It's all invested in and directed at him.

I've never felt this before. I've also never felt someone else's drool in my hand.

Our support crew tends to Mosi as he sits on a watercooler that couldn't keep ice frozen for more than 90 minutes because it couldn't keep pace with the heat. After 10 minutes, he wakes up, looks at me and asks, "You ready, KC?" I grab two water bottles and we keep it moving through the dark, rolling hills. I don't know where he summons the strength.

MAYBE YOU'VE SEEN the documentaries or heard the tales. Or maybe this is the first time you're reading about this kind of masochism. This is Badwater 135. Known as "the world's toughest footrace," Badwater is a 135-mile ultramarathon through Death Valley, California, home of the hottest air temperature ever recorded on earth.

And this is Mosi Smith.

It's hard to describe him without it sounding like a first-time rom-com screenwriter's description of Jane's love interest. Mosi, 36 and African-American, is a well-dressed Southern gentleman who is intelligent, fun, clever and thoughtful. He is a picture of health: a lean but muscular build, his head shaved totally clean, and the rare face that looks equally good with or without facial hair. When he smiles, an angel gets its wings. And did I mention he enjoys recreational candle-making?

Don't roll your eyes at me. Because it's not even like that. Mosi's just that dude. We're roughly the same age, but Mosi is who I want to be when I grow up. Aside from my mom -- which is, you know, hallowed ground -- he's the most selfless person I've ever met, always giving people advice, encouragement or his time and energy. I don't know where he gets the drive or the strength.

He's always working hard. Always serving others. Always moving forward.

Mosi is one of 99 endurance athletes running Badwater 135 in July 2018. He's way too humble to let me say it to his face, but the dude is a badass. Not only is he a Naval Academy graduate, a Marine Corps veteran and carved from the hardest, densest oak tree, but he also has completed more than 50 ultramarathons, including two previous Badwater 135s.

Mosi wanted to improve his Badwater PR by more than two hours, shooting for an ambitious time of 30 hours (average of 13:20 per mile). And before you act like that's not fast, allow me to politely remind you that we're talking about 135 miles in the dead heat of July. In the dragon's mouth they call Death Valley.

Still not impressed? OK. Well, the race also includes 20,700 feet of cumulative elevation gain and loss, as runners climb from Badwater Basin, the lowest point in North America (282 feet below sea level), to the portal of Mount Whitney (8,300 feet).

It's beyond intense. Ignoring the obvious challenges of chafing, blisters, cramps and fatigue, runners risk dehydration, rhabdomyolysis, heat exhaustion, heatstroke and organ failure.

To help them stay alive, these superhuman runners bring a support crew. Which is why I'm here, sweating through a reflective construction vest, putting cold cloths on Mosi's head and building a weird relationship with three dudes I met a few days ago.

What a crew.

LIKE MOSI, OUR crew chief, Arylis Scates, is former military, which you know before he even opens his mouth-the close-cropped high and tight is a dead giveaway. But that he's from Alaska? That's a fun surprise to bring to Death Valley. Arylis is the most useful person I could dream up for this scenario, an Army vet and internal medicine nurse who loves staying organized, driving above the speed limit and repeating a mantra that is also a command, "Everybody love everybody."

There's Ricky Haro, an Air Force vet from Arizona, outdoorsman and doctoral student who also has run ultramarathons through deserts. NBD. I take to him quickly because he's a generous laugher and he keeps everything lighthearted. But the best thing about Ricky is that he's the Goldilocks of motivation -- not too patronizing, not too harsh. Juuust right.

And then there's Sterling Becklin, who looks exactly like his name should be Sterling Becklin -- you know, like a Ken doll from Oregon. He's the quiet, enigmatic guy. The chill guy. The guy who didn't need to be involved in every handoff and interaction to feel useful. Also, the generous guy whose company sponsored Mosi and who picked up every tab, every rental and every $8 bag of ice.

So if Arylis is in charge, Ricky's the coach and Sterling's the banker, then what does that make me? I am the motherf---ing wild card (pounds chest and looks toward the sky).

I'm the only woman. The only Badwater rookie. The only one who had never crewed Mosi in a race.

But what I lack in experience and testosterone, I make up for in boundless energy, giggle fits and swaggy, naive overconfidence. I'm in my element. This is where I belong. Out here in the middle of a beautifully dystopian "Mad Max" hellscape, I'm everyone's punk-ass tomboy little sister. You want me on that wall. You need me on that wall.

I'm not exactly sure how I got the invite, but I think Mosi wanted to take a chance on me, to show me the limits of human endurance. He's the whole reason I got into ultrarunning in the first place. When a mutual friend introduced me to Mosi back in 2010, I had run a few marathons, but I wanted to go longer. I just didn't know how to start, how to train or whether I had the mental and physical composition.

Then Mosi took me under his wing, answering every question. How do I adjust my training for a 50-miler? What should I be eating during the race? What is this weird feeling on the outside of my foot?

And now, eight years later, it's not as if my questions have stopped. If anything, they've gotten harder. But Mosi makes it all seem simple. Because, honestly, it is. If you don't mind working your ass off. If you don't mind waking up at 3 a.m. to squeeze in a 20-miler before work. If you love the feeling of depletion and regeneration. If you actually kind of enjoy suffering, then ultrarunning is your sport.

So to be able to support my sensei at a race as notoriously difficult as Badwater? I've never been so honored to get so sweaty and tired.

Which brings us right back to the mission.

MOSI'S WAVE OF the race started at 11 p.m., in the blackness of a desert night. Since then, our vehicle has been leapfrogging Mosi every 2 miles to get him whatever hydration, food or supplies he needs. By the time he completes 62 miles -- the first 60 almost entirely uphill -- the temperature has not dropped below 105 degrees. Not once.

Mosi looks strong and focused through the whole push, staying pretty close to his goal pace, despite the fact that we're slow-roasting at 120 degrees. And though the temperature keeps climbing, the terrain is pointing downhill for the first time in many hours. But that doesn't mean it's about to get easier.

If you've run ultramarathons, you know that downhills tear your quads to pieces, grind your knees to a fine powder and elevate your heart rate. After 60 miles, downhills hurt. But Mosi wants to keep running. Despite the fact that he's overheating, he still wants to push the pace. "You don't understand," he says. "I can't slow down because then I'll stop."

“You don't understand. I can't slow down because then I'll stop.” Mosi Smith

This is the first time I've ever known Mosi to be worked up about anything. When he says it, he's seated beneath the liftgate door of our Tahoe, trying to stay cool in the limited shade while we swarm him with ice, calf massages and watermelon.

It's no surprise that after 60 miles of climbing uphill at an impressive clip, Mosi's engine is running hot. He's taken down plenty of fluids but hasn't peed in a few hours, which is cause for concern. Arylis explains it's because Mosi's internal processes have prioritized cooling over other functions, like processing waste. So his kidneys are on hold until his core body temperature drops sufficiently. Biology, man.

Our crew's priority is keeping Mosi cool, since his body can't seem to do it alone. We've increased our frequency of stops to every mile to load him up with ice, spray him down with water and provide some shade. All the while, the sun keeps pounding.

And don't give me any of that "it's a dry heat" garbage. This isn't some pleasant escape from humidity. There are road signs warning drivers to turn off their air conditioning so that the cars don't overheat and break down. Which is pretty similar to what's happening to Mosi's body.

At one of our crew stops, we pull over and another vehicle pulls behind us, running its air conditioning, pumping hot air from the grille of the car into our faces. "Don't f---ing run your AC up on this bitch," Mosi says, toggling away from his usually positive vibe to keep-it-real mode. We all laugh and pile it on among ourselves, but Mosi's sarcasm lands the haymaker. "It's a black and yellow sign, so it's just like, you don't have to f---ing follow that motherf---er. It's just a recommendation."

We're not actually angry at the other crew, but using them as the scapegoat is easier and more diplomatic than taking it out on one another. It feels like we've been standing under a hair dryer for 17 hours. That's no exaggeration -- we're actually 17 hours into the race when Mosi crosses the completely unprotected, sun-drenched Panamint Valley, where this year's runners are subjected to the hottest temperatures ever recorded during a Badwater 135 race. The air is 127 degrees, but the road is 159 degrees. That's basically the same temperature as a well-done steak.

Sterling is the first to hop in and pace for a few miles, helping push Mosi to the checkpoint at Panamint Springs (mile 72.7) by 4:08 p.m. On account of our frequent stops, Mosi's pace has slowed considerably. But he keeps moving, so we keep moving. Arylis jumps in with Mosi for a mile or two, as the course begins climbing again through the Panamint Hills.

But now it's my turn. And, bro, I'm going long.

AT THIS POINT, Mosi is walking because his body has nothing left. And honestly, what can I even say right now? I can't ask him "How you feeling?" because I know; I can see it in his gait. He is quiet, focused and pretty miserable for the first 5 miles, up a steep embankment, where the temperature is still 115 degrees and the slope feels pretty damn close to that.

When we see our crew, I pop on a vest with built-in speakers and put on a playlist. Lots of Childish Gambino -- Mosi's favorite -- peppered in with other hip-hop and R&B jams that help pass the time as the sun begins to set. He stops to stretch his calf, then drops some unwanted news on me. "KC, I'm gonna be honest with you. After we get up this push, I'm thinking about dropping."

I'm not having it. I'm just not. Not on my watch.

"Well, let's just keep doing whatever it takes to prevent that from happening," I say. We press on, and I hope he forgets saying those words to me. I hope that when we get to the finish line, we can both laugh at this moment.

Luckily Sam Cooke's "Bring It on Home to Me" comes on my playlist, and Mosi can't help himself. He's singing along. Then we're straight up dueting, alternating the low and high "yeah" notes at the chorus. And though the song lasts less than three minutes, it changes the whole vibe.