200 Marathons in 100 days

A world-record-breaking endurance challenge, running 200 marathons in 100 consecutive days to raise £1 million for brain injury charities Headway UK and Head for Change.

The challenge will begin on 29 May 2026, the day after Jackson’s 44th birthday, and conclude on 5 September 2026.

Jackson will run two marathons every day for 100 consecutive days, covering more than 8,450 kilometres — the equivalent distance of running from London to Los Angeles. The attempt is expected to break the current men’s world record for consecutive ultra-marathons, a feat that has never been achieved before at this scale.

But for Jackson, this challenge is about far more than records.

In 2013, his professional rugby career was abruptly ended by a traumatic brain injury. The road to recovery was uncertain, and at times, simply returning to normal life felt impossible.

“Everyone thinks this challenge is impossible,” said Jackson.

“But I believe in IN-possible. That belief runs deep — and it’s something my recovery taught me.”

It took seven years after his brain injury for Jackson to run his first-ever marathon. Now, more than a decade later, he is attempting 200 marathons in 100 days — a journey he describes as both physical and spiritual.

The challenge draws inspiration from the Marathon Monks of Japan, whose legendary endurance practice traditionally takes seven years to build toward, culminating in a final year of extreme distance running.

“This feels like my own spiritual journey,” Jackson said.

“My injury took something from me — but recovery taught me how to turn something bad into something good.”

A huge part of Jackson’s recovery involved running and breathwork, tools that helped him rebuild both body and mind. But he is acutely aware that not everyone affected by brain injury has the same access to recovery, rehabilitation, or long-term support.

“I’ve experienced first-hand what recovery can look like — and I’ve also seen what happens when people don’t get that chance,” he said. “That’s why this challenge is for Headway UK and Head for Change — and for the people whose lives are changed forever by brain injury.”

The route has been deliberately designed to bring people together across the UK. Jackson will run at 25 locations throughout the UK, spending four days at each site, completing the daily distance through 5km and 10km loops.

The loop format allows anyone — runners, walkers, first-timers or experienced athletes — to join him, whether for 5km or further, and take on their own version of the IN-possible.

“This isn’t just about supporting from the sidelines,” Jackson added.

“It’s about being involved. Running your own little IN-possible.

Whether it’s your first 5km or something much bigger — this is about believing in yourself again. And drawing on the support of each other – as I’ve experienced strength is multiplied when shared.”

Jackson hopes the challenge will inspire people to reconnect with the mindset many have as children — the belief that things are possible.

“Somewhere along the way, we stop listening to that little voice that says ‘yes, you can’,” he said. “This challenge is a chance to listen to it again” – because he believes “we are far more capable than we allow ourselves to believe. It’s time to start believing in ourselves and what’s possible again, together.”

Challenge facts at a glance

· Challenge: Mission IN-possible – 200 Marathons in 100 Days

· Dates: 29 May – 5 September 2026

· Distance: 8,452km (equivalent to London → Los Angeles)

· Format: 2 marathons per day for 100 consecutive days

· Route: 25 UK locations, loop-based for public participation

· Charities: Headway UK & Head for Change

· Fundraising target: £1,000,000

· Goal: World record + awareness for brain injury recovery