A single photo can flip your life. That’s where John Castle’s story begins—49 years old, 45 pounds heavier, borderline diabetic, and staring at a version of himself he didn’t want to keep. Fast forward to today and John is a force in obstacle course racing, stacking Spartan Ultras, conquering World’s Toughest Mudder, and chasing Barkley dreams with an approach built on simplicity, routine, and a ruthless mindset.
We dig into the craft behind his late-career rise. John lays out his daily hill—900 feet from his front door to the county high point—and how he threads running with functional strength: burpees at half-mile marks, rock carries, rope climbs, pull-ups in the woods, and box jumps on a cable spool. He explains why he quit the gym, modeled training after top OCR athletes, and switched to high-rep bodyweight work that solved decades-old knee pain and sharpened his grip, durability, and efficiency.
Race day strategy gets real. John talks pacing a 50K with 60 to 70 obstacles, keeping his heart rate honest, and using transitions to refuel without ego. He shares what didn’t work (carb loading) and what did (beet juice, steady hydration, clean habits). We unpack the art of not quitting: finishing a lap with a fractured finger, course-finding at the Barkley Fall Classic by reading footprints in mud, and staying composed when fatigue blurs judgment. His take on aging is refreshing—best fitness at 58, faster times through consistency, and zero interest in shrinking goals.
If you need a shove to recommit or a template to rebuild, this conversation delivers practical, repeatable ideas: build a route you can start daily, align training with your event, keep the work simple, and let consistency do the heavy lifting. Listen, then tell us the one habit you’ll change this week. Subscribe, share with a training partner, and leave a review to help others find the show.

Thanks for listening to Running With Problems. Follow us on Instagram @runningwithproblems. DM us there with questions in text or audio messages! Or email us at [email protected].
Hosted by Jon Eisen (@mildly_athletic) and Miranda Williamson (@peaksandjustice). Edited by Jon Eisen. Theme music by Matt Beer.