Tough Mudder: A great away day?
It is perhaps not everyone's idea of team bonding, or a great company away day, but the founder of Tough Mudder is banking annual revenues of more than $100m (£58m).
Last year, nearly a million people around the world paid up to $200 (£116) to run, jump, swim, crawl and haul themselves around a 10 to 12 mile military-style obstacle course.
In the events, organised by the New York-based firm, participants are confronted by icy water, mud, live electric cables and barbed wire.
Will Dean, Tough Mudder's founder and chief executive, spoke to the BBC's Aaron Heslehurst.
- From the section Business