ABC News caught up with Demong a few weeks ago as he trained at the White Pine Touring Center near his home in Park City, Utah. It was early in the morning, the snow was falling fast and a heavy snow overnight was burying Demong's cross country skis. But none of that stopped him from racing up and down the hills.
"I enjoy my training. It's my lifestyle. I don't take time off," he said. "Even when I'm on the beach on vacation, I tend to go for a run every day. It just helps me feel better."
Between cross country skiing and the ski jumps, he spends about four to five hours a day on skis. Add in other land-based training and it's a full schedule.
Nordic combined is a small sport, and the American team has lived together in the same city for years, first in Steamboat Springs, Colo., and in Park City since 2002. The idea is that the novice and veterans train together and push each other.
"It allows us to bestow our knowledge on the younger guys," said Demong, who at 29 is considered a veteran.
Park City's 7,000-foot elevation is also a plus.
"One of the reasons to live up in the mountains as an endurance athlete is to utilize altitude as a training mode and to increase your aerobic capacity," Demong said.
Demong grew up in upstate New York and was cross country skiing by the time he was 5.
"Cross country is one of the easiest winter sports to do. All you need is a pair of skis and a little bit of snow. Growing up, I did a lot of skiing in our backyard," Demong said.
Just two years later, he met Larry Stone, a ski jump coach who showed him and other skiers a rough video, set to music, about ski jumping. He was hooked and started training at Lake Placid, N.Y., the site of the 1932 and 1980 Winter Olympics.
It seemed like a natural fit. Demong was born a month after the 1980 Olympics and people upstate -- and across the country -- were still rejoicing over the U.S. hockey team's surprise win against the Russians, the so-called Miracle on Ice.
Demong grew up driving past the two massive ski jumps that sit close to the highway leading into Lake Placid and and remembers seeing those jumps "looming over the village" and feeling the Olympic lure.
"It's the worst place in the world to grow up, because you stare at those towers your whole life," he said. "I was always sort of immersed in Olympic feeling."
For a young athlete in the days before the Internet, Demong said, "it was like winning the lottery to find some video of somebody jumping on an international level."
Today, the sport has a big online following, and aspiring athletes can track the pros' progress daily.
"I get Facebook messages every day from 13-year-olds saying, 'good job,'" he said.
Demong said there is nothing quite like flying off a ski jump, but that first jump can be very intimidating.
"When I was young, I was really afraid," he said. "It took me a few days of standing at the top the run before I actually had the nerve to push off the bar."
Even today, there is "always a flutter of the heart" before taking a jump.
"It really feels like flying," said. "We travel upwards of 450 feet in the air, most of it horizontal, actually. You feel the pressure of the wind on your skis, on your body and you just lay on it as if you were a human hang glider."
Demong said the Olympics are completely different than any other competition.