In the 1994 movie "Forrest Gump," the title character takes off running one day and doesn’t stop for more than three years.

When questioned about his rationale, Gump explained: “That day for no particular reason, I decided to go for a little run. So I ran to the end of the road. When I got there, I thought maybe I’d run to the end of town … no particular reason, I just kept on going.”

Like Gump, Tyler Johnson found running by accident.

When Johnson and his wife moved to Denver from the suburbs two years ago, they joined a downtown pub run to meet people in the city, enjoy a beer and perhaps partake in a little jog around town. As it turned out, this social event would inspire a passion for running — one that would lead Johnson to tackle a 100-mile ultra-marathon less than two years later.

Johnson is a water treatment lead at Denver Water’s Recycling Plant, where he identifies process and equipment improvements that increase the plant’s efficiency and decrease operating costs. It’s a job that requires meticulous analysis and research, skills that Johnson also uses off the clock as he strategizes and trains for long-distance trail runs.

“Until two years ago, I ran short distances to stay fit, but I definitely wasn’t in love with running,” Johnson said.

That’s when he made a friend at a Denver pub run who introduced him to trail running, and Johnson's passion exploded. “It was all over for me. I was hooked,” he said.

Johnson ran a 10K leg of the Colfax Marathon and immediately increased his distance to 50K races.

“I didn’t know I could love running that much,” Johnson said. “When you feel your legs on fire and your capillaries burning in the back of your throat as you climb a mountain, then you’re tearing down the hill almost faster than your legs can carry you — it’s like a controlled recklessness. After that first adrenaline rush, I just fell in love with running.”

During the summer of 2016, Johnson attended a beer festival that happened to take place at the finish line of the 100-mile Run Rabbit Run ultra-marathon in Steamboat Springs — a race boasting 20,000 feet of elevation gain. At first, the thought of running 100 miles seemed ridiculous, but as he watched runners cross the finish line, Johnson knew he would be signing up to run the race the next year.

Training for a 100-mile race isn’t easy. After a long day at work, Johnson would drive out to a trail and run 10 to 30 miles every day. He’d get home exhausted and starving, but happy.

“This last year I learned so much about myself and also running strategy, how to fuel my body — and I tore through running shoes,” he said.

Johnson described his mental state when running long distances — often well into the darkness of night — as a rollercoaster of emotions.

“It’s a game of strategy and mental endurance,” he said. “There’s a lot of time to think. You think about your pace, when you should eat and drink, your life, work, your training, friends, vacations. And sometimes your thoughts turn to the negative and you tell yourself ‘this is stupid; I’m never doing this again.’ Then, you pop a piece of candy in your mouth and just keep going.”

It’s an attitude that has kept him focused not just during training, but also through disappointment. While running his first 100-mile ultra-marathon in Steamboat, Johnson’s hip began to swell after 50 miles, and sciatic nerve pain prevented him from finishing. He stopped at mile 75.

Despite the setback, Johnson plans on tackling a 50 and 100-mile race this year. “There are still several races on my list. Running is medicinal for me. I just can’t stop.”