The word ‘Sisu' is a Finnish concept, for which there is no literal English translation, though it can be loosely described as the ‘ultimate determination, fortitude, and persistence, carried to an unfathomable level'. From this concept, SISU Endurance was born in 2011, founded by Death Race finisher and Joe de Sena pal Daren de Heras in Los Angeles, CA. De Heras has a long history with OCR and endurance events, dating back to the beginning of Spartan Race and the original Death Race events. He formed SISU Endurance after DNF'ing his first Death Race, but falling in love with the type of athlete who showed up at these events: the ones who never complained, but only asked ‘what's the next task?'

His goal with SISU was to create events that welcomed all level of athletes but challenged each to push their limits and realize their full potential. The first SISU event, The Iron, was created. An overnight hike with weights and challenges along the way, it was considered extreme, at the time. Since then, it has evolved into a 30+ hour, ever-changing and always unique yearly event, and remains the pinnacle of SISU Endurance. Other annual SISU events include the FORGE (a 12+ hour overnight ruck), El Cucuy (a Halloween-themed overnight event), and the SISU 24, a 24-hour event, in which the competitors run (or hike, as the case may be) as many miles as they can, and gain extra points along the way by completing specific challenges. This year, the 24 will be expanding and will include the 24 PNW, which will take place in the Pacific Northwest in June.

Though he has enjoyed success in the world of endurance-style events, de Heras wants to make clear that SISU events have never been about its leader, but rather about the athletes, coaches, community leaders, and volunteers who have tirelessly worked together to make these events what they've become: endurance events that not only push the body and mind, but seek to create a gathering of like-minded individuals who possess a tenacity of purpose, and the grit and determination that is SISU. I recently sat down with Daren to find out what makes him (and SISU) tick.

What was the inspiration behind the creation of SISU Endurance?

I formed SISU Endurance simply to give back the gift that coaches, friends, and loved ones had given to me. It has never been about my personal vision of a particular athletic event. Anyone can tell someone to grab a heavy ruck and do f**ked up stuff all night, but we want this to be an experience. We want it to mean something to each person. There is something magical in the human spirit, and I feel the word SISU is a representation of that. We don't care if you're the world's most elite athlete or someone who is just curious and wants to explore your own grit. All we ask when you come to a SISU event is that you come with the attitude that whatever must be done will be done, regardless of cost.

What has been the biggest reward of putting on these events?

Personally, SISU saved my life. It was the SISU community that lifted me up when I felt I was at my lowest while battling anxiety, depression, and addiction. SISU has never been about me or what I've accomplished. It is a community of people with the strongest collective resolve you'll ever find. They band together, they fight till their last breath. It is because of that love and generosity of spirit that I will soon celebrate my third year of sobriety. I consider myself lucky to be a small part of the SISU community. The events, the honesty, the sincerity, the tears. All of it.

How do SISU events differ from typical endurance-style events?

With so many different races and events out there, there is truly something for everyone. Some are beat-downs, some tell you that you won't finish, but each has its place. We try to center all our events around a heartbeat, and each one is different. We pride ourselves in having a staff with a wide variety of backgrounds, and we change and evolve the events as needed. This approach allows us to keep growing, and make sure that the events are not about any one person's singular vision. You can get a glimpse of what a SISU event is like on YouTube or Facebook, but to know for sure, you have to come experience it for yourself. You'll be asked to bear your heart and soul, and we know that's not for everyone. Some people prefer a more straight-forward approach, but our hope is that this will leave a distinct and positive impact on your life.

What is the background of the typical SISU athlete?

What I love most about SISU is the wide variety of athletes we attract at our events. When we first began, I think some got confused with the name, our image with skulls and hammers, and perhaps even my personal background and experience. But SISU has never been and never will be, about being some kind of a bad-ass. It is devoid of ego. All we ask is that each athlete, regardless of their level of experience, push themselves till they have nothing left. Then they get up and they give more. That is SISU. In my days as a young wrestler, I always knew that would never be the strongest or most athletic, but what I could be, was the last guy to be carried out of the wrestling room, when he couldn't even stand. To me, that's who the SISU athlete is.

What are your plans for the future of SISU Endurance?

This year will mark the eighth SISU Iron. I try and take each day as it comes, and keep one foot in front of the other. Running an organization like this, where there is no profit, where all involved are asked to do it because we want to give back, can be tough. But when you find those who share your vision, magic happens. Right now, we have plans for at least a ninth and tenth Iron. Beyond that, we'll see what the community wants. If the desire is there, we will march on. With the addition of the 24 PNW, the SISU 24 has turned into something I never dreamed possible. We have a new event location, and that's opened new doors for us. We're going to keep events like the FORGE and El Cucuy for those who like to get their ruck on, and hopefully continue to expand events like the 24, by bringing it to several more locations. This Labor Day, I'm working on a whole new thing that has never been done in our community. I can't speak too much about it yet, but just know that there is something new and big coming from SISU, that will challenge you and involve the whole family. We want SISU to grow, to be about the people who make up the community, and to make a difference. That, to me, is an honor and a privilege.

The eighth annual SISU Iron will take place May 3-5, 2019 at Camp Eaton, in Pearblossom, CA. Go to for more information. Use discount code MRG98 for 15% off your SISU Endurance registration.

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