27 Hours, 133 Kilometers, Zero Excuses: An Ultramarathon Through the Eyes of a Senior ARS Engineer

Interview with Luka Čanji

At first glance, engineering projects and ultramarathons don’t seem to have much in common. One happens in front of a screen, the other deep in nature, often stretching into the late-night hours, at the edge of endurance. But when you talk to our colleague Luka, a senior engineer on the ARS team and an ultramarathon runner who completed a 133 km race, you start to realize the similarities run deeper than expected. In this interview with Luka, we don’t just talk about kilometers. We explore mental battles, planning, unexpected challenges, and the kind of discipline that separates average from exceptional, both on the trail and at work.
His story is brutally honest, but also incredibly inspiring. If you’ve ever wondered where the limits of human endurance lie, and what’s on the other side, this is a story you won’t want to miss.

1. Many colleagues ask why you do this. Now that it’s over, are you any closer to an answer?

My colleague Vlada said to me: “I just don’t understand why people do this.” I didn’t know how to answer then, and honestly, I still don’t. Because if I truly understood, I probably wouldn’t be doing it.
Maybe I do it to try to understand. I don’t have a rational explanation for why, with so many obligations in life, I choose to run a 133 km race that took me over 27 hours to finish.

2. How would you explain the difference between a marathon and an ultramarathon – not just in distance, but in mindset?

I used to run traditional marathons of 42.2 kilometers, and people often ask why that wasn’t enough for me, why I always feel the need to push further. Usually, they mean in terms of distance. But for me, it’s not about the numbers. The real challenge is increasing the number of variables I can influence to achieve the best possible result. In a marathon, the main variable is physiology, familiar parameters like VO₂ max, lactate threshold, and so on. You hit your physiological ceiling pretty quickly. And as life responsibilities increase and the years go by, those values naturally decline. Nutrition and race tactics play a much smaller role.

In ultramarathons, especially those over 100 km, the number of significant factors grows drastically. Physiology is still important, but now nutrition, mental preparation, the ability to adapt to unexpected situations, and the discipline to fuel and hydrate regularly under extreme fatigue, all become crucial.

3. What does preparation and mental setup look like before a 133 km race?

It was hard for me to even get out of bed at 5 AM to catch the bus to the race start. I remember thinking, “Why am I doing this?” Since no answer came, I decided to just stop thinking about it.

Last year, I dropped out of this same race, and the mental pain of quitting lingered for a long time. This time, I was determined to finish, and I managed to rein in my competitive ego. That desire to “race” can really throw you off. I tend to focus too much on results early in the race, rather than sticking to the discipline that actually  gets you to the finish.

This time, I started calmly and strictly followed my nutrition plan:

• • every full hour: energy gel
  • at 1:20: four salty crackers
  • at 1:40: a wafer
  • Coca-Cola at every aid station – non-negotiable.

4. What did the race itself throw at you, and how did you handle the challenges?

Right at the start, the first surprise: massive mud. The first steep climb, I saw people slipping and unable to make it up, it was that slick. I immediately accepted that conditions would make the race harder and slower. I slipped, crawled, improvised, but managed. The first half of the race went well, given the circumstances. My stomach held up, I was eating and hydrating on schedule, my legs felt fine, and things were flowing. Then night fell. I turned on my headlamp and slowed down significantly. The mud became even more dangerous because I couldn’t see where it was. Suddenly, my foot would just slide out from under me. I fell and scraped my hand on some rocks, another hit to my rhythm.

At the Bešenovo Monastery, I ran into ultramarathoner Tanja Stojanovski. We continued the race together. We reached Andrevlje, a major aid station at kilometer 85, and the place where I had dropped out the previous year.
The volunteers immediately recognized me and started joking. This year, they had even set up beds and blankets by the fire, something they hadn’t done before. They told me they did it because of me, because they remembered how rough it had been for me last year, how I was shaking for an hour and couldn’t stop.

That was a turning point in the race. It’s where your mind breaks a little, especially knowing you’ll be back there again in about 20 kilometers. This time, I didn’t let myself stop. We kept going immediately. They wouldn’t even let me look at the fire, so I wouldn’t be tempted to lie down.

5. What was the hardest part of the race – and what was the most meaningful?

After leaving Andrevlje, another blow: my Garmin watch froze and shut down. I completely lost track of time. I thought it was around 1 AM but it was actually 4.
It became clear that I had lost my fueling rhythm and had been eating far less than planned. I wasn’t sleepy, but I was completely exhausted. I couldn’t run anymore, just walk.

Tanja and I returned to Andrevlje again, and that’s when I hit my first major crisis.
Dawn was breaking. We took a longer break there, and a few runners passed us, we lost fourth and fifth position.
Then came the climb to Crveni Čot. That’s where I was hit by intense sleepiness for the first time. I started hallucinating, seeing things in the forest. That was the hardest part of the entire race.
After Čot, I started jogging slowly and managed to pull myself together. I finished the race walking, crossing the finish line in 27 hours and 35 minutes. I’m very grateful to Tanja for her support and companionship.

6. How did you feel the day after the race? Were you satisfied?

I finished the race on Sunday around 12:30 in the afternoon. The whole day I felt foggy from lack of sleep. I dozed off a few times, but couldn’t manage to get into deep sleep. By Monday, it felt like nothing had happened, just one night less sleep over the weekend. My legs hurt surprisingly little. I was a bit more tired than usual, but I functioned normally.

7. After everything, did you say, “Never again”? Or are you already planning your next race?

This was my first ultramarathon in the 100-mile category. There are many beautiful races of that length in the region. This one was a test for me, to see if I could handle something like that with only modest training.

Right after the race, I thought the result of that test was negative, that I wasn’t built for it, because I had struggled a lot. But for years, I’ve had my eye on the Jahorina ultramarathon, where the course goes from the Montenegrin border to Jahorina in Bosnia. After the race, my wife said, “You’re not seriously thinking about the Jahorina ultra now, are you?”
At the time I told her I wasn’t ready for something like that. But now, as time passes, I think I was wrong then.

I just hope the organizers don’t change the longest-distance route for 2026.

8. How do you connect races like this with your work as an engineer?

The key is discipline, both in racing and at work.
At the start of a project, everything feels easy. You have energy, time, and motivation. Things move forward while waiting for the client to finalize the specification. But as the project progresses, challenges start to build – shifting priorities, tighter deadlines.

That’s why it’s essential to stay disciplined early on: to work methodically, prepare thoroughly, and build momentum while things are still smooth. In ultramarathons, you manage your pace, conserve energy, eat and hydrate consistently, and address issues before they grow. In engineering, it’s the same: you anticipate the client’s needs, think ahead, and stay focused on consistent execution. That steady approach ensures confidence and reliability, especially when the complexity increases.

Luka’s story is much more than a physical accomplishment. It’s a reminder that the most valuable lessons often wait for us where it’s hardest: in the mud, in the silence of the night, at kilometer 133. Or in the moment when a client is late with specs, and you remain calm, because, like Luka, you’ve already run your inner race.