This will be fun: http://toughmudder.co.uk/

Tough Mudder events are hardcore 12 mile-long obstacle courses designed by the Special Forces to test your all around strength, stamina, mental grit, and camaraderie.

Although i do enjoy a good set of monkey bars, and have a particular penchant for cold showers and ice baths, the real reason our team "Chafing the Dream" have put ourselves up for this is to raise funds for The Royal Marsden Cancer Charity. Having been affected by the cancer of family members and colleagues, we as a team have chosen to support the Royal Marsden, a specialist, world class facility that provides  treatment and care to thousands of cancer patients, to allow them to continue their fantastic work in patient care as well as cancer research.