A self-described ultrarunner who does triathlons (not the other way around), john Kelly will be racing Saturday in Kona.

John Kelly has a pretty strong mental game. This past April the 32-year-old data scientist became only the 15th person ever to finish the Barkley marathons—approximately 130 miles of thrashing through Tennessee wilderness— within the 60-hour cutoff. Exhausted and sleep-deprived at the finish, Kelly had the wherewithal to offer a plausible explanation for why he was wearing a plastic Walmart bag ala shrug.

A self-described ultrarunner who does triathlons (not the other way around), Kelly will be racing Saturday in Kona as a very competitive age grouper, with Team Every Man Jack.

He fits recreation like the Barkley in around a full-time job with a startup company, and a startup family—three children under 4 years old. That’s where we run smack dab into the equally formidable but less sweaty Jessi Kelly, and how he does it all becomes clearer.

Both the Barkley and the Kona World Championship Ironman require supreme physical adaptation, but more than the physical, extreme endurance events like these require a super strong personal CEO. Kelly talked by phone about the differences in the mental game between the Barkley and an Ironman triathlon.

Triathlete: What are some differences in mental preparation for Barkley and for an Ironman?
Kelly: A lot of it is similar in that it takes mental strength to do the repetitive things necessary for success. As far as training for Barkley, once I got things figured out, it was less disruptive to my life. I could get in all my miles super early, on the treadmill in my basement, or as part of my commute.

With triathlon, you have to consider your relative passion and strength in each of the disciplines and weigh that against available time. I don’t enjoy swimming, I’m not good at it, and it doesn’t work into my commute. You can invest a ton of time, go from a good to a great swimmer and save ten minutes. Or you can go from a good to great biker and save an hour. I also have to weigh whether it might be more beneficial to get more sleep [he gets by on six or seven hours] rather than get up and go to the pool. It builds mental strength being consistent and efficient in working training around family life and job responsibilities.

Triathlete.com: How about differences in racing?
Kelly: Finishing Barkley is an experience unlike anything triathlon has come close to. Qualifying for Kona was about like finishing the Barkley Fun Run [approximately 65 miles in less than 40 hours].

Ironman still has a large mental component but it’s a different type of pain—you’re going for a shorter distance at a higher intensity. The cutoff time for Barkley is 60 hours; for an Ironman, it’s 17 hours. I’ve never got to the point in an Ironman where I thought I should quit, but you do have to recognize your relative strengths and weaknesses. In the Ironman 70.3 World Championship, I came out of the swim in 781st place and finished in 99th place. When I come out of the water, I think, now my race begins. My goal is to not lose too much on the swim, gain on the bike, and really catch people on the run. I can’t get caught up in racing someone who has different strengths.

It’s much easier to get into a dangerous spot in Barkley: You can be on the first lap and start thinking, I’ve got to do this for the next 55 hours? In an Ironman, even if it’s hot and miserable on the run, you can think, okay, two more hours and you’re done and you can eat ice cream and cool off.

There are a slew of logistical things that can go wrong in Ironman—getting a flat is one of my biggest fears—but for the most part the only thing you have to think about during the race is pace. There are not that many unexpected obstacles in triathlon. The course is controlled, and the amount of time you’re racing is significantly less than at Barkley.

Barkley is a different animal. The hardest part is convincing myself to keep going and not shut down, not give in to fatigue and exhaustion over such a long time period. The amount of things that can go wrong is vastly greater, the fatigue is cumulative. Even though you’re racing for a much longer amount of time, sixty hours is actually a tight cut-off. In Barkley, there are just so many decisions you have to stay on top of—navigation, clothing, where can I get water, what will I be able to eat 40 or 50 hours into the race? There are so many things that can go wrong, that you have to plan for and adapt to, all while you’re sleep deprived and less able to make those decisions. You just can’t stay on top of everything.

What about loneliness? In an Ironman, there are other athletes and spectators the whole way; Barkley seems a lonely challenge.
I was with Gary [Robbins] for a lot of Barkley. It is helpful to have a second person there for navigation but in the end, it’s an internal mental battle. You have to fight those demons on your own. If someone’s having a rough patch, it can bring you down, so having company isn’t always helpful. Of course, an Ironman is a different experience. Some people key off of crowd support. I’m kind of intrinsically motivated; crowds are not a huge factor for me. Having other competitors, people to try to pass drives me, for sure.