Then, not only did he get up and keep running — he also finished third.
Last Friday, the 35-year-old was going strong as he reached mile 56 of the Hardrock 100, an ultramarathon in Colorado's San Juan mountain range that is known as of the world's most punishing runs.
It was at that point that he found himself going up a ridge toward Handies Peak, which is, at 4,285 m (or 14,058 ft), the race's highest elevation point.
"There's something fun about getting to the high point in a race, you can tell yourself, 'oh, it's all downhill from here,' even though it's 12 hours of downhill," he told CBC Radio One's Rick Cluff of The Early Edition.
"I was already starting to get tired, obviously. I'd been running for 14 hours."
As the sun set, a storm started to roll in.
Campbell could see that it was an electrical storm that was brewing.
There was no shelter — it was well above the treeline, and there were no big rock outcroppings — so Campbell was fully exposed to the elements.
Then, as he came within 200 meters of the summit, a bolt of lightning struck the peak.
"It was terrifying," he said. "It looked like this tentacle of light bathing the summit."
Campbell's friend, ultramarathoner Aaron Heidt, was with him through this leg of the course for safety.
Nowhere to hide
As there was nowhere to shelter themselves, Campbell decided their best option was to keep moving.
They both went flying when the next bolt struck.
"The moment we hit the summit, it was like a gunshot went off right by my ear — this incredibly white flash of light — and the next thing I knew I was lying on the ground," he said.
Campbell says the two knew instantly what had happened.
"You could just hear this crackling electrical sound all around us," he said.
Heidt and Campbell checked each other for injuries, and luckily neither was wounded.
"It obviously wasn't a direct hit," he said. "It was some sort of an impact right next to us, something had rebounded up and gone through the ground and had given us a jolt."
Campbell says he felt himself starting to have a panic attack, but calmed himself down, knowing he had to get down from the summit.
As Campbell continued down the slope, he was able to pick up his pace. He finished the race in third place, which he calls a huge personal accomplishment.
"My feet are still tingly, I guess."
Despite the gruelling conditions, and the danger of being exposed to the elements, Campbell say running an ultra-marathon is worth it to him.
"My mantra is 'I'm suffering in beautiful places, so it's not so bad,'" he said. "It's a deep sense of challenge, there's not a lot of things in our daily lives that really take us out of our comfort zones, especially not if you work in an office environment. I find that this does."