Ko te juri? Kilometers That Change Children's Lives

There are moments during a run when we stop thinking about pace, results, fatigue and the kilometers left to the finish. That is when we become aware that it is not only the strength in our legs moving us forward, but the reason we started in the first place.

For participants in the humanitarian KTJ challenge, that reason often has a name, a face and a family waiting for good news.

Their kilometers do not end on Strava, in a results table or on a medal hanging around their neck. They become donations for children's medical treatment, visibility for their stories and reassurance that families going through the hardest periods of their lives are not alone.

The story of “Ko te juri?”, better known as the KTJ challenge, grew from exactly that idea. In just a few years, it developed from a small circle of friends into a seriously organized humanitarian project with almost one thousand participants.

At its head is Sanja Mitić, an event manager at the IT company RT-RK, a lifelong athlete and a runner who now races almost every weekend, most often on trail courses. She is currently preparing for the Amsterdam Half Marathon, which will be her first true experience over the 21-kilometer road distance, but her most important result cannot be found in any official race table.

It lives in the people she brought together and the help that community has managed to provide.

Running as a School of Character

Sanja says she has been running practically her whole life, although her sporting journey has taken her through different disciplines. She began in team sports and later found herself in individual challenges, through which she continued discovering her own abilities, limits and reactions when things become difficult.

Sport has never been merely physical activity for her. Through training, competitions, victories and setbacks, she also developed as a person, learning that progress is most often the result of a long process that cannot be rushed.

Completing long distances and demanding training sessions, she explains, says a great deal about a person's character. The discipline to get up when we do not feel like training, the persistence to continue when results do not come quickly enough and the willingness to show up every day carry over into every other part of life.

Running taught her to trust the process, not to give up as soon as the first obstacle appears and to understand herself much better.

When we know our limits, but also how to move them gradually, it becomes easier to navigate professional, personal and emotional challenges. That ability to endure, organize and continue would later become one of the foundations of the KTJ story.

The Idea That “Got Out of Hand”

KTJ did not begin as a large project, a carefully designed system or an organization with dozens of people. It started spontaneously among Sanja's closest friends, from a wish to use sport to do something good for someone who truly needed help.

The first editions had no official applications, complicated forms or precisely defined hierarchy. Participants gathered through private messages and group chats, while most arrangements were based on friendship and personal trust.

In January 2023, the KTJ challenge brought together around one hundred runners.

The number of participants then grew with every edition, and the organizers' responsibility grew with it. Once the community passed 300 runners, it became clear that the project could no longer function solely through the enthusiasm of a few people and agreements made in messages.

A system had to be built.

Today, the regular KTJ challenge is organized twice a year, along with a special edition for companies known as the KTJ Business Challenge. Around one thousand runners are expected to take part in September 2026, while interest is already greater than the organization's current capacity.

They are runners from Serbia, Montenegro, Croatia, North Macedonia, Bosnia and Herzegovina, other European countries and different parts of the world. Some complete their first one hundred kilometers during the month, while others manage to record more than one thousand.

Yet regardless of differences in fitness, speed or experience, every participant contributes to the same goal.

How Does the KTJ Challenge Work?

The essence of the challenge is simple, but its value comes from a large number of people acting together.

Each participant donates at least 1,500 dinars directly to the account of the child for whom that edition is raising funds. Over the next thirty days, runners record their kilometers, share the child's story and encourage other people to become involved through donations, sharing posts or participating themselves.

In September 2026, the community will run for a boy named Vuk Arapović. The aim is to use thousands of completed kilometers to draw attention to his treatment and raise as much financial support as possible.

During a single month of the challenge, the KTJ community can raise more than five million dinars, showing how large a result can emerge when many small contributions are directed toward the same goal.

Someone will run ten kilometers, someone one hundred, and someone will set a personal record of several hundred. Someone will not run but will make a donation. Someone will share a post that reaches a person ready to help.

That is exactly where the strength of the entire idea lies.

We do not all have to contribute in the same way, nor does our contribution have to be large to be valuable. It is enough to do what we can, because every individual step connects with the steps of others and sets a much larger mechanism in motion.

More Than 55 People Behind One Challenge

As the number of participants grew, so did the organization that is not always visible in photographs, posts and results.

Today, the KTJ team includes more than 55 people who volunteer their time and knowledge. At the center of the project is a coordination team made up of Sanja, Petar Petrov, Aleksandar Stajić and Dušan Krstić. The wider organization also includes supervisors, team captains, result controllers and other members responsible for communicating with participants, verifying results and keeping the challenge running every day.

Instead of a public draw or random allocation, captains now form their own teams and choose the members for whom they will be responsible throughout the month. This way, every participant knows whom to contact, while the organizers have a clearer overview of the large number of people, activities and results.

All participants use Strava to track their kilometers, but serious technical work sits behind that simple recording of activities.

Members of the Serbia Run team play a special role, and Sanja particularly highlights Aleksandar Lazović and Dušan Vostić. They collect, process and analyze every runner's results, making it possible to keep an accurate record of kilometers throughout the challenge.

The developers working on the system also volunteer their time alongside their regular jobs.

That is one of the greatest challenges KTJ faces. The project has grown large enough to require almost daily involvement, yet it still relies primarily on people who perform their duties because they want to contribute to the community.

That is why finding runners is no longer the biggest problem; there are more of them every year. The real challenge is finding people willing to treat the organization as a serious responsibility for several months, even though they are not financially compensated for it.

The Hardest Decision Is Not Organization, but Choosing the Child

When discussing a project that brings together one thousand people, it is easy to assume that spreadsheets, applications, communication and processing results are its most demanding parts.

For Sanja, however, the hardest moment is choosing the child for whom the community will run.

Behind every application is a family, medical documentation, uncertainty and parents trying to secure treatment for their child. It is impossible to view such stories only administratively and without emotion, especially when it is clear that help cannot reach everyone at the same time.

For that reason, the organizing team decided to help children in order, according to the parents' applications and the community's capacity.

The most emotional moment of each edition comes at its conclusion, when organizers and participants meet the child for whom they have spent the previous weeks running and raising money.

Sanja says those moments are difficult to describe in words.

Everyday worries often seem smaller then, while things we normally take for granted acquire a completely different value. The children for whom funds are raised have a chance of receiving treatment, but often lack sufficient financial support from the system, making help from individuals and the community essential.

That is when it becomes clear that behind every result on Strava is a real life that result can change.

A Community Built on Friendship, Not Popularity

Sanja particularly emphasizes that KTJ did not begin as a community centered around an influencer, a popular individual or a desire for personal promotion.

Its foundations are friendship, mutual trust and years of working together.

She met most of the people who make up KTJ today personally through sport, races and organizing the challenge. The team's hierarchy was not created to give anyone a more important title, but so that every member would know their responsibilities and almost one thousand participants could function as a connected community.

Numerous friendships, connections and relationships have emerged through that process and continued after the challenge ends. Runners come from different cities, countries, professions and sporting backgrounds, but for one month they share the same goal.

That is why KTJ's value cannot be measured only by the amount of money raised or the total number of kilometers.

It can also be found in the people who began running regularly for the first time, in participants who completed their first 100 kilometers thanks to the team, in those who discovered how persistent they could be, and in friendships that might never have existed without this challenge.

The KTJ Relay as a Gathering of the Community

Alongside the monthly challenges, KTJ organizes its own race once a year: the KTJ Relay.

It brings together participants from the January challenge, their families, friends and everyone who wants to meet the community and experience in person an atmosphere that exists mostly through Strava, groups and social media during the rest of the year.

Organizationally, the relay is less demanding than a month-long challenge involving hundreds of activities every day, so team members jokingly call it their “easy work.” Still, it too involves a great many details, agreements and people working to give every participant the best possible experience.

Partners and sponsors play an important role, enabling the organizers to provide products and cash prizes for the top competitors.

Sanja acknowledges that finding support is not easy today, because sporting events take place almost every weekend and many races compete for the attention of the same companies and partners.

Still, she does not see the growing number of races as a problem.

The more events there are, the more opportunities people have to find a discipline, distance or community that suits them. The most persistent will have space to stand out, recreational athletes will have more choice, and physical activity will gradually become part of everyday life.

Movement should not be an occasional project we return to only before summer, a race or an important date. It should be a natural part of our day, like caring for ourselves without questioning whether it is necessary.

Do Not Wait for Perfect Conditions

When asked what advice she would give someone who wants to start a similar initiative, Sanja does not talk about large budgets, perfect systems or thousands of participants.

Her advice is to begin with a small group of people.

Do not wait for the ideal moment, because it will most likely never come. Be consistent, treat every responsibility seriously and build the community step by step.

KTJ began with a few private messages sent to friends. There was no large team, no results-processing system, no network of captains and no thousand registered runners.

There was only a sincere idea.

Over time, other people recognized that idea and added their time, kilometers, knowledge and contacts until it became a movement capable of raising millions of dinars for a child's treatment in a single month.

That may be the most important message of the KTJ story.

When Kilometers Gain a Greater Meaning

In the running world, we often talk about personal bests, medals, pace and goals we want to achieve. All of these are important parts of sport because they motivate us to improve and show ourselves what we can do.

Yet some kilometers teach us something even more important.

They are the kilometers we do not run only for ourselves.

Perhaps that is why the challenge is called “Ko te juri?” — “Who is chasing you?”

What chases us is the desire to finish what we started and to show that solidarity does not always have to look like a grand heroic act.

Sometimes it looks like one more kilometer run.

When that kilometer joins thousands of others, it stops being only a distance and becomes hope.