Six British and US servicemen have run across the US - from New York to California - to raise money for wounded military veterans, the BBC's Katie Connolly reports.
Colour Sgt Damian Todd doesn't even like to run. "I hate running. I absolutely hate it with a passion," he told the BBC.
And yet he has just led a team of six servicemen - five marines and a British Army member - on a 3,530 mile, eight-week running odyssey, passing through three deserts, four time zones, 10 mountain ranges, 16 states and 789 towns across the US.
Colour Sgt Todd dubbed this trek "the Gumpathon", after the film Forrest Gump, where the title character runs across America. Colour Sgt Todd liked the idea when he saw the film 14 years ago, and stashed the seemingly fanciful notion in the back of his mind for a later date.
That date came on Christmas Eve 2007, when Royal Marine Mark Ormrod stepped on a land mine in Afghanistan and lost both his legs and one arm.
Inspired by the courage and strength of amputees like Marine Ormrod, Colour Sgt Todd revived the idea of the Gumpathon as a way to raise money for wounded veterans.
The Gumpathoners - five Brits and one American - started off at the USS Intrepid in New York City on 10 September and finished on the Santa Monica Pier in California on 11 November - Remembrance Day, or Veterans Day.
Each day - rain, hail or shine - they ran anywhere up to 88 miles, keeping an average pace of 10 minutes per mile or less.
Most days, they ran relay-style for about 10 hours, with one runner completing 10 or more miles before handing off to the next.
Other days they set personal challenges. Master Gunnery Sgt Charles Padilla, the one US Marine, achieved a personal goal of 85 miles (137 km) in one day, which sparked a friendly trans-Atlantic rivalry.
Refusing to be outdone by an American, Army Staff Sgt James Mazzoni-Dalton ran 86 miles. Egged on by his fellow Brits, he completed the run in 19.5 hours. He was so exhausted when he finished around midnight that Colour Sgt Todd had to carry him to his bed.
On his prosthetic legs, Marine Ormrod usually ran one gruelling mile at a time. His prosthetics have no knee joints so he had to run with stiff upper legs - a much more physically taxing style.
Over the course of the Gumpathon, his fitness and endurance increased so dramatically that some days he managed to run up to five miles in one stretch.
Colour Sgt Todd snapped his Achilles tendon just before leaving the UK, leaving him unable to run. He completed his legs of the relay using a hand powered recumbent bike he's affectionately nicknamed "Achilles".
"I have to say, my upper body is quite buff now," he jokes. He has lost at least 11lb (5kg).
Another Gumpathoner, Cpl Lloyd Renner, has lost almost 25lb (11kg), even though each runner has been chewing through about 6,000 calories a day. They have eaten anything - chocolate bars, cookies, pizza - just to get those calories in.
Only Staff Sgt Mazzoni-Dalton had ever completed a marathon before the Gumpathon - which is the equivalent of 34 marathons for each runner. Colour Sgt Todd says he deliberately sought participants who weren't experienced runners to make the achievement even more impressive.
Sadly though, despite their astonishing endurance, the Gumpathoners are falling short of their fundraising goals.
"Every one of us has picked up at least one injury," Marine Jamie Jobson wrote on the Gumpathon blog last week.
"Our bones ache first thing in the morning and last thing at night, we have blisters, shin splints, clicking ankles and knees, bruised heels, colds… the list could go on but I'll round it up by saying we're all hurting, but all of this will be in vain if we don't raise as much money as we can for our chosen service charities."
But Colour Sgt Todd says the idea of quitting never entered his mind - even when running uphill on a humid 110F (43C) day in West Virginia, getting frostbite in his fingers on a chilly night in California or struggling against the driving rain in New Mexico.
His spirits are buoyed by the people he has met and the generosity of the communities they have passed though - many have provided food, shelter and donations.
Among his memories are highs like being cheered by onlookers as he crossed the Hoover Dam, and lows like getting a flat tyre on the downhill stretch he had been longing for on the Chesapeake Bay Bridge.
But an Arkansas man holds the honour of making the biggest impression on Colour Sgt Todd. After hearing what the Gumpathon was about, the man turned to Colour Sgt Todd and told him: "You're the most remarkable man I've ever met."
Upon hearing such a positive affirmation of his work, Colour Sgt Todd, tired to the point of breaking, had just one response: he cried.