Endurance Athlete Shares Secrets to Long Mountain Careers

Jack Kuenzle discusses training, FKTs, and the decision-making that defines long efforts in the mountains.

Published on Mar. 5, 2026

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Endurance athlete Jack Kuenzle didn't come up in the typical proving grounds of mountain sport. Much of the training that built him into one of the fastest athletes in the mountains happened far from alpine terrain, grinding away in the flatlands of coastal Virginia. That unconventional start shaped a mindset defined by ruthless efficiency and a willingness to strip training down to what actually works. Since leaving the military in 2021, Kuenzle has translated that approach into some of the most competitive fastest known times in the mountains. But for Kuenzle, the pursuit isn't just about records - it's about the quiet calculations behind them: preparation, pacing, risk, and the long process of learning how to move through the mountains efficiently.

Why it matters

Kuenzle's story provides insight into the mental and physical preparation required to excel in endurance mountain sports, which are often framed as pure suffering. His emphasis on decision-making over pure fitness highlights the importance of experience and problem-solving in a discipline where a single mistake can be fatal.

The details

Kuenzle trained extensively on pavement, stair machines, and treadmills in coastal Virginia, rather than in the mountains. This allowed him to optimize his training and eliminate unnecessary elements. He sees the "suffering" of endurance sports as a byproduct, with the true motivation being ego and the desire to realize one's vision of being fast and great. When deep into a multi-hour effort, Kuenzle focuses on breaking it into smaller, achievable chunks to distract himself from the pain.

  • Kuenzle left the military in 2021 to coach and compete full-time.
  • In 2024, Kuenzle set the ski FKT on Mont Blanc despite poor conditions.
  • In September 2022, Kuenzle broke Kilian Jornet's record on the Bob Graham Round.

The players

Jack Kuenzle

An endurance athlete who has set some of the fastest known times (FKTs) on major mountain routes and peaks, including the Presidential Traverse, Mount Shasta, Denali, Rainier, and the Bob Graham Round.

Kilian Jornet

A renowned mountain runner and ski mountaineer whose record on the Bob Graham Round Kuenzle broke in 2022.

Colin Haley

A professional mountain climber known for his long and successful career in the sport.

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What they’re saying

“I really enjoy the cognitive side of mountain sport. For FKTs especially, there's a huge amount of planning and preparation involved; thinking through routes, gear, pacing, and logistics.”

— Jack Kuenzle (tetongravity.com)

“If you are coming up in mountain sport in your 20's, it's a very dangerous time. At some point, you will find yourself in a situation that you never thought of or no one warned you about.”

— Jack Kuenzle (tetongravity.com)

What’s next

Kuenzle plans to continue pursuing FKTs and other endurance challenges in the mountains, with a focus on longevity and decision-making over pure speed.

The takeaway

Kuenzle's approach to endurance mountain sports emphasizes the importance of efficient training, risk management, and cognitive skills over pure physical fitness. His story provides a model for young athletes seeking long, successful careers in these demanding disciplines.