For any of us, completing a marathon is among the toughest challenges we will ever take on.
Imagine running six...across the Sahara desert...on prosthetic legs. That's exactly what double amputee Duncan Slater is hoping to do next month.
We've been following his preparations, as he gets ready for the gruelling Marathon des Sables in Morocco.
For Duncan, ensuring his prostheses don't rub is essential.
It's what ultimately meant he was unable to complete the race last year.
Incredibly, he was forced to give up on the last day, after his stumps became so raw he was warned he risked serious further injury if he carried on.
This year, he's got a secret weapon - new cutting edge prosthetic legs made in Italy.
The legs are made with all the skill and imagination you expect of Italian bespoke design.
Silvio Galfione is described by Duncan as a "Jedi Knight" of prosthetics.
He's developed a new technique to ensure his prosthetic legs fit very precisely even when the wearer is running.
Duncan is confident most of the rubbing will be eliminated by these new carbon fibre legs.
The key to the process is that Silvio takes a millimetre perfect impression of Duncan's stump while he is standing up.
That means his muscles are under load and it gives a much more realistic set of measurements.
The contours of Duncan's stump are mapped using a special machine which uses high pressure air to form a perfect seal around his skin while he has a wet plaster cast on.
The resulting tightly fitting cast is then removed from his leg and used to make a facsimile of his leg in plaster.
This is 100 % accurate template is then used to make a plastic socket which is then coated in super-strong carbon fibre. It's akin to a handmade rigid sock which fits perfectly.
Silvio has pioneered this technique near Milan, but he and his partner are hoping it will soon be available in the UK.
As Duncan says, it has been life-changing for him, eliminating all rubbing and enabling him to run for hours without any pain at all.
He hopes to prove that not only will it mean he can finally complete the Marathon des Sables in April, but also that these super well fitting prostheses will eventually be made available to anyone in Britain, increasing their mobility and reducing their aches and pains.
Donations to Duncan's fundraising page can be made here.