Sport Relief raises money for vulnerable people in the UK and in some of the world's poorest countries.
We've been hearing for months about what challenges celebrities and people all over the UK are planning to do to raise money.
Helen Skelton has trekked 500 miles across the South Pole in freezing temperatures, David Walliams swam 140 miles down the River Thames in London and comedian John Bishop biked, rowed and ran from Paris to London - nearly 300 miles in just five days!
We asked you what you were doing for Sport Relief. Here are a selection of your comments.
"My school did a 26 minute marathon where you could hop, jump or do anything you wanted to."
Samantha, 10, Birmingham, England
"I am making a dance routine with my friends to show in London! I am also doing a huge bake sale in school! This year I want to raise lots of money! So far I have made £340!"
Kristy, 11, London, England
"At school we had to walk around our two massive fields three times or more! And we had to carry buckets on our heads to see how hard it really is. We had a really fun day!
Joe, 11, Worcester, England
"I'm giving up talking until Sunday."
Sharna, 11, London, England
"I am doing a cycle from my school to Africa and hope to make lots of money for Sport Relief."
Sealintim, 10, Brighton, England
"We did one mile for Sports Relief around the school field and my friends tied rope to the feet of my wheelchair."
Skye, 12, Buckinghamshire, England
"I cycled 50 miles for Sport Relief! I'm really proud of myself and I thoroughly recommend raising money to everyone!"
Joe, 11, Greater London, England
"Me and my friend have been busy baking brownies and cookies for the past two days! We have made over £30 and we still haven't finished!"
Caitlin, 11, London, England
"In my school we got to decorate eggs and brought in a pound for Sport Relief. It was so much fun!"
Emily, 9, Liverpool, England
"My swimming club is doing a mile swim for Sport Relief and we've raised £3,500."
Ryan, 11, Buckinghamshire, England
"I did no talking for a whole day at school, plus I didn't get told off for it."
Malak, 10, Birmingham, England
"I'm skipping for two hours 40 minutes and already raised £80."
Natasha, 15, Sheffield, England
"I am going to run 3 miles for Sport Relief with my cousin. Thank you to everyone who sponsored me!"
Poppy, 13, Newcastle upon Tyne, England
"I had an own clothes day at my school today. Everyone gave a pound to wear whatever we wanted all day! It was fab and we raised lots of money for Sport Relief."
Nandi, 14, West Sussex, England
"Lewis Street Primary School are raising money for Sport Relief and I have run a mile, which is 7 laps and exhausting! I've raised £34 and I'm so pleased I can help people!"
Sophie, 10, Greater Manchester, England
"I have been set a challenge to record a few of my favourite songs for Sport Relief whilst some other people at Brinsworth Comprehensive have done stuff like sponsored silences, cycled around the park etc. On Thursday we will all run a mile around school in fancy dress!"
Olivia, South Yorkshire, England
"The students of Yateley Shotokan Karate Club are doing a mile of Karate in the Camberley Shopping Centre - our team total so far is £1158."
Tom, 11, Hampshire, England
"I did a quadathlon at school which involved 16 lengths swimming, 400m rowing, 400m running and 8 laps of an obstacle course."
Hannah, 11, Nottingham, England
"My primary school dressed up as Olympians and did a fun run, martial arts and a dance. We also did a teachers' race where you had to guess who was going to win."
Rebecca, 11, Edinburgh, Scotland
"I am doing a mile around the rugby field at school and it is going to be fun because we get to dress up."
Linda, 13, Greater Manchester, England
"We're getting dressed in costumes and doing a mile run."
Samia, 13, London, England
"At Craigie High we have been running the Sport Relief mile."
Declan, 15, Dundee, Scotland
"Over 300 pupils from Newdale Primary School in Telford have walked to the top of a nearby hill with sports equipment and dressed in red and white. The children have collected many sponsors and the local authority catering staff, supported by the army, made a kitchen on the summit and fed everyone pasta and bolognese sauce."
Miss Clifford, Year 6, Telford, England
"We are dressing up in cool costumes and doing a fun run!"
Tom, 15, Hertfordshire, England
"I am going to run around the field and give £1 to take part. I am so excited and I am sure we will raise lots of money."
Saima, 15, Worcestershire, England
"Cossington Primary School in Leicestershire is taking part in a Sport Relief mile around the school field. Children can stay after lessons and complete six laps in order to achieve a mile! They will donate £1 to take part. Good Luck!"
Mr Law and Class 3, Leicestershire, England