If you asked Shannon Craig how she felt about finishing her first Spartan Race moments after she crossed the finish line, she’d tell you to ask again in 10 days. She needed time to process what happened during those 9.5 excruciating miles at the Colorado Super. “I did more than finish that race,” she says now. “I finished the races of my life.”

Like many new Spartans, the 30-year-old single mother of three and nuclear medicine technologist from Fort Collins felt undertrained—the race was three times longer than any run she’d ever done. But she had a particular reason to be worried: Despite never having done a Spartan Race, she’d accidentally signed up for the elite field. And watching an elite Spartan quit the race with a twisted ankle unnerved her further.

If only she could call Harlan Mekelburg, the 68-year-old skin cancer patient who’d originally told her about the obstacle race, and ask his advice. She’d been prepping Mekelburg for a PET scan when the former Ironman began talking about the mud, the walls, the camaraderie. Mekelburg was a fighter, and he was refusing to give in to an ugly diagnosis. It wasn’t unusual for Craig to be inspired by the toughness of her patients, but Mekelburg, with his weekend races, was a particular kind of strong.

“Here, in front of me, this 68-year-old man who is undergoing treatment for a life-threatening disease is running and completing Spartan races,” Craig says. “I questioned what I was doing with my own life.”

That was in December, and Craig began training straight away, running three miles after putting the kids to bed and stealing sets of pushups in the back room of her office. But come race day five months later, she was afraid. And once she started racing, negativity flooded her psyche. She was in pain. This is on par with childbirth, she thought, and she considered calling it quits. Who would care if she decided to have a beer and relax?

“If I’m being transparent, I must confess that there were moments where I thought to myself, ‘What did I get myself into?’ and ‘Why am I doing this?’ in the same breath,” Craig says.

She tried to overpower her doubts with positivity. “Just keep going,” she thought. But it was becoming harder. The pain and discomfort threatened to overtake her strength.

Then, midway through race, she found a source of unrelenting strength: Harlan Mekelburg. The 68-year-old patient who first inspired her appeared suddenly next to her on the course. The encounter was unplanned and unexpected, but in that moment, with Craig being in over her head and plagued with doubt, his presence was exactly what she needed.

“God is the only answer I have to how perfectly orchestrated it was,” she says.

They slogged up the final quad-searing hill and saw the finish line. Craig finished the monkey bars and waited for Mekelburg, who—unable to do the bars—opted for burpees instead. There was no way Craig was going to race ahead of the man who brought her to this beautiful moment of personal wonderment. Together, the two jumped over the fire and crossed the finish line.

Pain and joy—that’s the short version of how Craig describes the feeling now. Hugging and falling over her oldest son after the race, her exhaustion was as emotional as it was physical.

But now that she’s had time to think, Craig can describe the feeling of finishing your first Spartan Race in full. “Competing in Spartan grants the privilege of humbling a person to a place where you recognize the value in human relationships,” she says, “and the glory in being all that you were created to be.”

Ready to give Spartan a try? Here’s everything you need to know to find your race.