And despite the business only starting in 2010, Tough Mudder says more than 2.5 million people have already taken part in the challenges.
The obstacles are wide-ranging and include mud traps, large walls and tunnels which runners are encouraged to help each other through.
"It was very refreshing to be sat next to two people I didn't know," Charlotte says."We organise rural singles' events such as regional pub grub nights, sailing trips and an annual ball." More than 300 people, mainly in their forties and fifties, attended the Mud Lovers ball last year."People come from all over the country and there's a seating plan done by area to combat cliquiness," Lucy says.You can sign up for the events by finding one the one closest to you by clicking here and following the links.Organisers don’t release the exact details of the obstacles before individual challenges to make the events more challenging.You can choose from a Mini Mudder or a Tough Mudder Half, up to the World's Toughest Mudder.The challenges are the brainchild of founder Will Dean who formed the idea while studying in America.But according to Patricia Warren, a farmer's wife from Derbyshire who runs the Country Bureau, a rural introduction agency, the country dating scene can be bleak, whatever age you are."Communities are small and people work long hours," she says. "I've gone to so many hunt balls this year, I've become a bit of a joke among my friends.Muddy Matches is an online community designed to bring together rural lonely hearts (see below)."The downside of hunt balls and race meets is they can be cliquey," Lucy says.