The hour-long programme will see celebrities Susannah Constantine, Tameka Empson, Jupp and Dennis push themselves to the limit as they embark on a mission to regain their fitness and help inspire the great British public to get active and do their part for Sport Relief too.

The show will follow the four of them over 10 weeks as they run, row and swim their way back to fitness. The programme will culminate in one of the UK’s hardest and most demanding physical challenges, which will see the four celebs tackle a muddy and exhausting obstacle course in freezing temperatures.

Helping them on their way will be former Olympian, world renowned sports scientist and physical activity expert Professor Greg Whyte OBE and Dr Zoe Williams, presenter of BBC Two’s Trust Me, I’m A Doctor.

The show will also feature visits to a number of Comic Relief funded projects in the UK. These projects are just some of the ways in which money raised through Sport Relief helps vulnerable people in the UK and across world to live happier, healthier and safer lives.

Famously Unfit… for Sport Relief is made for BBC Two by Little Gem. It has been commissioned by Patrick Holland, Controller, BBC Two and Tom McDonald, Head of Commissioning, Natural History and Specialist Factual. The Commissioning Editor is Diene Petterle.

Liz Warner, CEO, Comic Relief, says: “Sport Relief is about all of us doing something active to help raise money for brilliant causes. But these celebrities have gone the extra mile - literally - and put their bodies publicly through extreme rigour. We can only celebrate their bravery, watch in awe and donate. Thank you Susannah, Miles, Tameka and Les.”

Ben Gale of Little Gem says: “We are delighted to be teaming up with the BBC, Sport Relief and the Famously Unfit…for Sport Relief team to demonstrate just how effective peer power can be in getting - and staying - fit. And with the added motivation of raising money for some very good causes."