When Hannah Cox set out to run 100 marathons in 100 days across India, she was not chasing a personal best.
She was chasing a line on a map, a forgotten colonial boundary, and a connection to a father she lost to cancer when she was in her twenties.
The 41-year-old had never even run a 5k parkrun. In fact, Hannah did not run at all.
The idea came about after she started reading Indian history books in a bid to learn more about her dad’s former homeland before he arrived in the UK as a child, with his British father and Indian mother.
One of the books that caught Hannah’s eye was The Great Hedge of India, about the Inland Customs Line – a 4,000-kilometre shrub barrier built by the British in India to control the salt trade.
‘It was just the craziest story I’d ever read,’ she tells Metro. ‘It was bigger than the Great Wall of China yet everyone’s completely forgotten about it.’
As the years went by, Hannah, who lives on a canal boat in Greater Manchester, couldn’t shake her obsession with the route and even went to the British library to find the only map of it, dated 1874.
‘I was completely fixated, so a friend eventually joked that I should run it. When I realised that the route finished just outside Kolkata where my dad spent his early childhood, I thought, “if I run a bit further, I could actually get to his house”.’
Despite having no experience at all, when she turned 40 in 2024, Hannah decided to give it a go – despite most people meeting her plan with disbelief.
But it wasn’t just about undertaking a personal pilgrimage and a world first, for entrepreneur Hannah – she also wanted to create something with lasting impact.
So Hannah found herself a running coach, launched a crowdfunder and launched Project Salt Run, with the aim of raising £1million for four environmental and social impact charities.
Hannah started her training by setting goals every month. She went from smaller runs to her ‘20 20 20 challenge’, which inolved covering running 20k a day during the week and 20 minute strength conditioning at the weekends for 20 days. Then she ran coast to coast across England covering seven marathons in seven days. To prepare for the gruelling Indian temperatures, Hannah also spent two weeks at a special lab running on a treadmill in a sauna.
Finally, in October 2025, she was ready to set off on her challenge with her crew of four, which consisted of a podiatrist, support runner, driver and helper.
As soon as she crossed the start line at the Pakistan border in the Fazilka district of Punjab, Hannah found it immediately challenging as she was running into traffic, often on national highways with no real rules. ‘It felt surreal, like I was in a movie,’ she remembers. ‘People were driving down the wrong side of the road. Then there were the cows, snakes and goats in the road.’
Meanwhile, thick smog from diesel fumes hung in the air making breathing difficult: ‘The quality was extremely poor. You could definitely feel it.’
During the day, Hannah would be followed by her crew van, while at night they would park up at night in petrol stations or by the side of the road.
And while her training had prepared her for the heat, Hannah was less ready for the continual sickness she battled and ended up losing eight kilos across the whole journey.
With no proper fridge and only roadside markets, she lived off eggs and whatever she could tolerate. Lentils and pulses – regular Indian staples – made her nauseous.
‘I would say I was sick for most of the trip.’ Hannah admits. ‘I just couldn’t keep anything down.’
Determined to keep her energy up, she forced herself to eat five meals a day, but on Day 49, she was badly ill and spent the night vomiting at the side of a petrol station forecourt.
Yet that wasn’t the runner’s darkest moment. That had come nine days earlier while Hannah was pounding the roadside and couldn’t stop the negative thoughts from creeping in.
‘I just remember wanting to give up. I felt like we weren’t getting any traction. We weren’t fundraising. I was worried we were wasting everyone’s time,’ she remembers.
Thankfully, her four-strong team kept Hannah motivated whenever she felt she’d hit a wall. ‘I couldn’t have done it without them,’ she admits.
But it wasn’t just exhaustion and sickness that proved dangerous. In forest regions, the police had to escort the team through areas known for big cats.
‘We joked that it would be lovely to see a tiger, but the police warned us: “you wouldn’t see a tiger. You’d just be dead”. Every week in that area someone was killed by one.’
Amid the chaos, there were also many moments of wonder, such as spending time at the Taj Mahal. Strangers would also wave Hannah down, giving her water or bananas, and regularly cooking for the team in their homes.
Hannah was also stunned that some of the 150-year-old road still existed, largely unnoticed, and the team even found a stretch of the original customs line, a herringbone path running beside a canal in Palwal. ‘It was an exact match to the map. It felt like discovering the pyramids,’ she explains.
By the end of her 4,220km journey Hannah’s body was used to running a marathon every day but with just 48 hours to go she developed a deep pain in her leg.
‘After 15km I genuinely went into the checkpoint thinking, I’m going to have to stop,’ she remembers. Fortunately, painkillers, tape and adrenaline carried Hannah through to her final destination: her father’s old home in Kolkata.
There, she found a broken sign from the building in a rubbish pile and rescued it to take home as a memento.
‘I don’t have many memories of my dad, so to get there on foot meant everything,’ says Hannah, who is still letting it all sink in. ‘I don’t actually know how I feel now. All I’ve focused on for two years is making this happen.’
With her fundraising goal of £1 million, Hannah is all too aware she needs to find a new way to keep momentum going. ‘Now it’s about building on what we’ve done,’ she explains.
When she first shared the plan, many people doubted her. One hundred marathons later, she proved something to them, and herself.
‘I didn’t give myself the option to give up,’ Hannah adds. ‘I just kept going.’
To donate to Project Salt Run click here.