My career as a musher ended the day it began. I was in Canada’s Yukon, desperately trying to look the part. I had grown a beard especially for my trip to the northern wilderness, and was dressed in a plaid shirt and jeans, and my oldest, grimiest baseball cap. The dogs weren’t fooled. They could sniff out cheechako — a newbie — in an instant.

Ned Cathers was my host, a 10-time veteran of the legendary 1,000-mile Yukon Quest, the world’s toughest dog-sled race. With calm efficiency, he rigged up a team of four dogs; they yelped with excitement. The sled was anchored to the ground with a snow hook, holding the dogs back.

“Okay, it’s done,” Ned said. “You ready?”

I nodded and took hold of the sled.

“You remember the commands?”

“Yes. ‘Gee’ to make them go right. ‘Haw’ to make them go left. ‘Whoa’ to stop.”

“Guess you’re set, then,” Ned said, though he appeared unconvinced. “The dogs sure are.” He released the snow hook. “Mush!”

I’m not quite sure what happened next, but apparently I had kept one foot on the snow. When the team accelerated down the trail, I remained rooted to my standing leg, and watched the sled trundle off empty. “Whoa!” I shouted in vain after the dogs.

“Too late,” said Ned, trying not to laugh. “They won’t hear you. If you were in the bush right now, you’d be in serious trouble.”

Fortunately, we were in the backyard of Ned’s cabin beside Lake Laberge. The trail was a circuit, and within five minutes the dogs were galloping back toward us. Ned flagged them down.

Second time lucky. I made sure that I was standing firmly on the sled when the command was given. “Mush!” Off we went at surprising speed. As we approached the first corner, I shouted “Haw,” though it was unnecessary. The dogs knew the route.

The cabin receded, and I was alone with the team. The sled rails rumbled beneath me; the dogs panted smudges of warm breath; 16 paws scuffed the icy ground. I imagined what it would be like to be embarking on the Yukon Quest, with two weeks of racing ahead of us, through forests and along frozen rivers.

Loneliness would bite soon. The mental struggle is every bit as tough as the physical one. Solitude and fatigue often conspire to conjure vivid hallucinations. Mushers watching their dogs’ feet for signs of lameness claim to have seen the paws kick up bright colors in the snow, “kinda like the Northern Lights,” said Ned.

Other mushers become convinced that they have a passenger riding with them and, compensating for the imagined extra weight, turn their sleds over on tight corners. That can be a disaster, because, as I had discovered for myself, the dogs don’t necessarily stop.

In recent years, the two major races, the Yukon Quest and the Alaskan Iditarod, have attracted protests from animal welfare activists, who contend that dog-sledding is cruel. Yet as I stood on the sled watching my team, I could see that these dogs were born to run. They clearly were loving it.

During the races, a posse of vets follows the competitors by air, ready to tend to any problems. As the race organizers are quick to point out, the medical contingencies for the dogs are far better than for the mushers.

For me, one circuit was enough. My face and hands were frozen by windchill. My thighs ached from absorbing the jarring undulations of the trail.

“How far did we go?” I asked.

“’Bout a mile,” Ned said.

Only 999 miles to go. I knew when to quit.