Now, we all know the benefits of running — whether we do it professionally, for recreation, or just to keep fit. But one man decided to transform his runs into a 100-day experiment… with pretty remarkable results.
While plenty of people flirt with a weekly parkrun or sign up for the occasional 10k, social media influencer Zack Telander went all in. No rest days. No easing into it. Just one mile, every single day, for 100 consecutive days.
And he didn’t just want to complete the distance. He wanted to get faster every single day.
Telander set himself a brutally simple rule: knock 10 seconds off his mile time each day until he physically couldn’t anymore.
The idea came to him in the most unglamorous way possible.
Speaking to Men’s Health, he said: “I decided to start running because I was actually on the toilet, and I thought, ‘Man it would be really cool to run a mile in 10 minutes today, and then try a mile in 9 minutes and 50 seconds tomorrow, 9 minutes and 40 seconds the following day’.
“Essentially, dropping 10 seconds each day until I can’t do it anymore. And then within the hour [of that thought], I was at the track running.”
READ MORE: FITNESS EXPERTS REVEALS HOW FAST YOU SHOULD BE ABLE TO RUN A MILE, ACCORDING TO YOUR AGE
No long-term planning. No dramatic YouTube build-up. Just a decision — and then action. He began on the first day of June. Within weeks, the streak had momentum.
By day 22, he was already deep into the routine. His body was adapting, even on days when motivation wasn’t exactly flowing.
“There were days definitely where I didn’t want to run,” he revealed. “And the one thing I kept saying was ‘You know you didn’t run’; I could be like, ah, well no one’s going to know if I didn’t do one of the days here – I could still say that I did the streak, but I would know. And I just remember saying that, it was really effective – I immediately put my shoes on and was like, alright, let’s go.”
That internal accountability became the difference.
In an era where nearly everyone seems to be chasing PBs, marathon medals or viral Strava screenshots, Telander’s challenge tapped into something simpler — consistency.
And the physical impact was significant.
After 100 straight days, the transformation wasn’t just about pace on a stopwatch.
“After 100 days, I feel great, and I will keep going because I worked this hard to gain this ability. Basically, when I started, I couldn’t run at this pace that I’m running at for longer than a mile and a half or two miles, and now I feel like I can keep going and going,” he said. “And it would suck if I was just like, ‘Alright I’m done’ and then I lost that ability. So I don’t know how much longer I’ll be able to do this, but I don’t see it stopping anytime soon.”
Endurance improved. Speed improved. But perhaps more telling was how it reshaped his overall training priorities.
Telander’s background isn’t endurance sport — it’s heavy lifting (and music). The professional musician revealed how strength work was his foundation. Yet as the challenge progressed, something shifted.
“Yesterday I ran 12 x 400 metre sprints at a pretty fast pace with only a minute in-between, and I didn’t even think about going to the gym later that night, so I think that’s more of what’s affected,” he revealed.
That’s not just improved cardiovascular fitness — that’s a fundamental change in athletic identity.
Running regularly is widely regarded as one of the best things you can do for your body, provided it’s approached sensibly. As per The Circle Health Group, running strengthens the immune system, with studies suggesting runners have a 25–40% reduced risk of premature mortality and may live around three years longer than non-runners.
It also significantly improves heart health by strengthening cardiac muscles, lowering blood pressure, improving circulation and reducing the risk of cardiovascular disease — with research showing that even five to ten minutes a day at slow speeds can cut the risk of death from heart-related conditions.
Running is also highly effective for weight management, boosting mental wellbeing through the release of endorphins, and it strengthens bones and increases bone density.
However, running should be approached with care to avoid injury and burnout. Overuse injuries are a real risk, so it’s important to increase distance and intensity gradually rather than overloading muscles and joints too quickly.
Wearing appropriate footwear suited to your foot type and running style is essential, as is alternating between different surfaces to reduce repetitive strain. Incorporating strength training and flexibility work can help protect muscles and joints, while maintaining proper running form improves efficiency and reduces injury risk.
Just as importantly, rest and recovery are crucial — allowing time between runs helps the body repair and adapt. Listening to your body and adjusting your routine accordingly ensures running remains sustainable, safe and beneficial in the long term.
Sure, a mile isn’t ultra-distance. But done daily, and done progressively faster, it becomes a serious physiological test. Speed work places high demands on the cardiovascular system, muscular endurance, and recovery capacity.
For those looking to improve their own pace, strength still plays a role. Runners Need suggests incorporating squats, lunges and deadlifts into your routine to build power. Speed sessions and hill training are also recommended to improve both endurance and top-end pace.
Featured image credit: Instagram/@zack_telander (screenshots)
