Last year, at 74, Nick Isenberg started a new career as a stand-up comedian.

By his 75th birthday in June, Isenberg did something even more extraordinary: He climbed Glenwood Springs’ Iron Mountain 500 times.

Blind.

His quest kicked off nine years ago, when he was a sighted 66 year-old simply looking for a new way to exercise.

“I hiked up and took the gondola down. I just did it once to see if I could do it,” Isenberg said.

The next summer, he climbed the three-mile Transfer Trail, the road up Iron Mountain, 19 more times. The year after that, he hiked it a whopping 29 times. And the summer after that, a heart attack left him legally blind.

“I was the second-most premature baby to live when I was born in 1942. I was 90 days premature, weighed 2 pounds, 11-3/4 ounces and was in an incubator for 10 weeks,” Isenberg said. “The doctor said [to my parents], ‘Give him a name so you can bury him.’”

He lived, but oxygen pressure in the incubator resulted in a lifetime of vision troubles. He’s now suffering the end-stage consequences, and his vision degenerates a little more each day.

Nevertheless, Isenberg was back on Iron Mountain the summer after his heart attack. While having coffee with a friend one day, he realized something.

“Gee, if I did this 15 times by June 10, I’d make it to 70 climbs by the time I’m 70,” he said to his friend. “Let’s see if I can do it.”

He did. By his 73rd birthday, Isenberg had hiked it 300 times; by his 74th birthday, he’d hit 400 and was on target to hit 500 climbs by the time he turned 75.

“I was really hustling. On July 4, I did it six times in one day,” he said. “Two days later, some plumbers left the trap door open at the bottom of my apartment stairs and I fell and broke my arm, messed up my rotator cuff and my vision deteriorated further.”

Determined not to put off his goal, he had a friend guide him up the mountain twice more that summer, his arm still broken. By the end of the season, Isenberg had hiked Transfer Trail 452 times. To reach 500 climbs, he had to summit the mountain 48 more times between March, when the snow melted, and his June 10 birthday.

It wasn’t easy—he had to work around bad weather conditions and a challenging course. In fact, he’s hiked to Mt. Everest’s base camp before and said that Iron Mountain is a more difficult climb. Despite the odds, he made it, thanks to a network of volunteers that rallied around his cause.

“I met a guy at the bus stop, and he said he’d help me, and then he was telling a friend about it and he said he’d help me, too,” said Isenberg. “I think I have 11 people helping me. Two guys did it two or three times in a day.”

His partners hike a few feet ahead of him with a rope tied around both their waists to prevent Isenberg from falling off a cliff (there are seven along the trail) or getting lost.

“Last year, I could see enough that I wouldn’t fall off a cliff, but I got lost six times,” he said.

Isenberg has no plans to climb Iron Mountain 1,000 times by his 80th birthday. Instead, he’d like to return to making documentaries, something his career as a reporter prepared him for. His next project gives viewers permission to remain active as they age. Isenberg said his role model for growing older is Julian Vogt, a cross-country skier who lived to be nearly 104 and was active to the end.

“You can get stronger and healthier as you get older,” Isenberg said. “At 66, I had to stop and keep catching my breath. It was easier to climb as many times as I did last year than it was once at 66.”