If you're thinking of getting involved, here are 5 physical challenges you can try.
Beat 1 billion steps a day
Not on your own, of course! Sport Relief is challenging the public to do a combined 1 billion steps each day from the 17th to the 23rd March.
It’s easy to join in - simply download the Sport Relief app which will track your steps and add it to the day's total.
The app allows you to compare your tally against your friends, so why not make it competitive and see who can do the most steps?
There’s already a competition between Harry Potter fans over which Hogwarts House can walk the most steps, which you can join here.
Cycle through work
Set up an exercise bike at work and raise money by cycling through the entire working day.
Take on the challenge with colleagues by creating a relay team and ask them for a small donation to take part.
Or test your endurance by pedalling solo for the day and ask for sponsorship. Just make sure you eat plenty of pasta the night before.
There are several organised 10k runs taking place across the capital during Sport Relief week, including Run UK’s Hyde Park event on Saturday 17th March and the Victoria Park Winter Series, on Sunday 18th March.
Find A Race is a good tool for monitoring what routes are available on specific dates.
If you’re new to running, check out our tips for beginners.
Row the River Thames
Stretching from Gloucestershire to the North Sea, the mighty River Thames presents a mammoth endurance task for keen rowers to tackle.
But instead of braving the elements to navigate its 215-mile course, you can cover the equivalent distance on a rowing machine at the gym.
Give yourself a week to complete the challenge, or recruit some friends and form an oarsome relay team.
Cycle to work
Ditch the car or say goodbye to the Tube and raise money by cycling into work for a week.
Ask your friends to dig deep to support your efforts and try to get your work colleagues involved too.
To boost your fundraising, use Steve Morgan’s Cycle to Work Calculator to see how much money you save, and add this to the final total.
If you work in London, some of our scenic cycling routes might inspire you on your route to the office.
Are you taking on any challenges for Sport Relief? Let us know on our Facebook page.