Gary Barlow and Gary Lineker unveiled Take That's "Greatest Day" as the official England 2014 FIFA World Cup song as part of Sport Relief.
London 2012 boss Lord Coe is returning to his days of sporting prowess - by trying his hand at rhythmic gymnastics for Sport Relief.
David Beckham has described how he struggled to sleep the night before making his Only Fools And Horses debut because he was so nervous
The Prime Minister, his wife Samantha Cameron and their children have run the Sport Relief Mile.
David Cameron and his family completed the Sainsbury's sponsored charity event at Cutteslowe Park in Oxford.
Mr Cameron said afterwards: "Sport Relief brings together some of the best things about Britain - we are a great sporting nation but also one of the most generous countries when it comes to contributing to good causes.
"This is the third time I have run the Sport Relief mile and I am delighted to have taken part in such a fantastic event that is bringing people across the UK together to get active, raise money and change lives."
Returning X Factor star Cheryl Cole has described her near death experience of malaria as she helps to raise funds to fight the disease through Sport Relief.
Cole claims doctors gave her just a day to live at one stage when she was struck down with the illness after contracting it on holiday in Tanzania. She said:
"When I climbed Kilimanjaro for Comic Relief five years ago it was honestly one of the hardest things I've ever done.
"The motivation lay in knowing it could help in eradicating malaria and ultimately saving lives by providing mosquito nets.
"I didn't for one minute think that only a year later I would get malaria myself and become so ill that at one point I was given 24 hours to live.
"It was the scariest thing you could ever imagine for me and for my friends and family. The pain I felt and went through, it's what so many people go through, all because they don't have a mosquito net which could save their life.
"I was lucky, I had the best care I could get. Some people are not so lucky."
Alan Shearer and Robbie Savage will tackle each other in a five-day Sport Relief challenge to see who can sit on 45,000 Wembley Stadium seats in the fastest time.
Shearer Vs Savage: The Battle of the Backsides will see the pundits divvy up Wembley Stadium's 90,000 seats from March 10-14 and attempt the sit-off, with each aiming to be the first to complete 45,000 chairs and reach the winning post, the royal box.
Estimates suggest that they will have to manage around 14 seats per minute across 10 hours each day in order to complete the challenge by the time the final whistle blows.
Match Of The Day star Shearer said: "Even at the peak of my career this challenge would have been tough on my body. However, now I am a retired footballer - so it's going to be a challenge of physical and mental endurance. I can't let Rob win; I'd never live it down."
Savage added: "Alan does have an advantage as his butt is larger than mine - but my bottom is ready for the challenge."
To support the challenge, members of the public are being encouraged to enter a competition at www.sportrelief.com/backsides with the chance to win tickets to see England play at the 2014 World Cup in Brazil, a day watching tennis at Wimbledon or a chance to see One Direction playing on tour.
Thousands of running enthusiasts joined celebrities and sports personalities today for the Sport Relief London Mile.
Conservative MP and former Strictly Come Dancing star Ann Widdecombe started the first wave of the charity run, which included Spice Girl Melanie Chisholm, model Nell McAndrew, EastEnders actors Matt Lapinskas and Tony Discipline and Olympic and Paralympic medallists Allyson Felix and Chris Holmes.
The Sainsbury's Sport Relief Mile is one of hundreds of runs happening around the country to raise money for the charity appeal.