Douglas Flynn, 27 from Holt, and Patrick Jenkinson, 29 from Belgium, are leading double lives.

By day, they have desk jobs in central London. By night, they are planning and training - sometimes for six hours when they get off work - for a charity challenge unlike any other.

The two friends will travel to Rwanda on September 6 for a series of self-designed disability events, including a wheelchair marathon, a blind marathon and a no-leg swim. Mr Flynn and Mr Jenkinson are competing unchallenged, but athletic glory isn't the goal. They're hoping to raise £20,000 for two charities, Handicap International and Motivation.

Though neither Mr Flynn nor Jenkinson are disabled themselves, both wanted to draw attention to the unique challenges people living with disabilities in a third world country face every day.

'There are tons of deserving causes in Africa but we felt really strongly about this one. Handicap International is a brilliant charity and Motivation provides wheelchairs to people in developing countries - they even donated some of their chairs to us for use in our challenge,' Mr Jenkinson said.

Training for the challenge has not been easy. For eight months Mr Flynn and Mr Jenkinson have been preparing by doing grueling workouts, made even more difficult because they're moving long distances in wheelchairs, running with their eyes covered and swimming with their legs tied together.

A lot of the training has taken place at the Weir Archer Academy, run by David Weir, the London-born wheelchair athlete who has won six gold medals in the Paralympic Games. Fittingly, the start date of the duo's challenge lines up perfectly with the Paralympics in Rio.

'The Academy really helped make our dream a reality, David is the best Wheelchair Olympics coach,' Mr Flynn said.

Though friends have told Mr Flynn and Mr Jenkinson to consider creating a public event of this kind in the future, for now they're keeping their eyes on the prize.

'We're just focusing on the challenge at the moment, and want to give a big thanks to our friends and family for being so supportive over the past few months,' Mr Flynn said.

To donate, visit http://www.triathlon-untested.org/.