More than 50,000 people have been running around north east England in the Great North Run.
Although there are some big-name athletes taking part too, most of the runners are doing it for charity.
They're pounding the streets for 13 miles to raise as much cash as they can.
So what have you done to raise money for others?
Have you been fun-running, or has your school school got involved in a charity?
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"I have done a sponsored bouncy castle jump at £1 per five minutes. All the money went to Dove House Hospice because my grandma died in there but she died happy so I want it to be famous."
Alastair, 10, England
"We ran two miles for charity and all wore fancy dress. It was so fun!"
Anna, 11, London, England
"I cycled 16 miles and raised £170 with my sister for the RSPB!!"
Hannah, 12, Scotland
"I swam five miles for charity without stopping. I had to sleep for two days after as my legs were so tired!"
Jessie, 12, London, England
"At school I am on a committee that organises charity events. We have done cake stalls and fun runs and dressing up. It is a lot of fun, especially when it is for a good cause!"
Emily, 13, Cambridge, England
"I can't do the races or stuff like that but any clothes that don't fit me or old Barbies that can still be played with we all give to our fave charity shops."
"I do the Race for Life every year. Last year I raised £500.00."
Abigail, 12, England
"I raised £50 for Scoliosis Research UK. I want to help other people like me who may have had/need the scoliosis corrective surgery or bracing. In the future I hope to walk the Tesco's run for Scoliosis charities."
Emma, 12, Gateshead, England
"I ran the Race for Life last year for Cancer Relief and this year my mum and I have organised a pink rose pudding party for Cancer Relief! It's really good and we always raise so much money for a really good cause!"
Marie, 12, Cambridge, England
"I once did a sponsored sleepover for the Macmillan Cancer Support at my local Brownie centre. It was great fun!! I also did the Junior Run around Manchester City Stadium!! Plus, I have raised money for Dogs for the Deaf!!!"
Rebecca, 11, Manchester, England
"Every year my family and I go on a charity run for people for cancer. At school, we also have a book week where people sponsor you to read the most books. We raised over $30,000!"
Alix, 9, Hong Kong, China
"I have done the Race For Life. I'm proud of myself, as I am not athletic."
Chrissie, 13, Dudley, England
"I give clothes away to Cancer Research UK because my nan died of cancer."
Katie, 11, Staffordshire, England
"At my primary school, we dressed up, had talent shows, a penny line race, the lot! I also did lots of the Blue Peter things and my brother did the Sport Relief mile."
Joanna, 12, Birmingham, England
"I had my birthday party as a fundraising party for Cafod. We had a big disco and I raised £144.20."
Alexandra, 10, Leeds, England
"At school, we had a charity day where our year group did outdoor games and raised money for a certain charity. When we did it, it was the Dogs' Trust. I did a refreshments stall and raised £200."
Adam, 12, Solihull, England
"I raised money for a charity when we had to do this thing at Brownies to get sponsors. I felt good when I did it because I knew that I had done something good for the world."
Maisie, 10, Scotland
"I have swam 2km for Marie Curie Cancer Care. It was great. I raised £120 in total. It took me 40 minutes to do."
Kieran, 9, Northumberland, England
"My school has done a water sports day in our pyjamas for a water aid charity."
Parris, 10, Southampton, England
"Me and my friend Ella raised £122 for Children in Need, by being tied together with a scarf for a whole day of school."
Francesca, Gloucester, England
"We dressed up in fancy dress for the tsunami a couple of years ago. We also had a coffee morning and lots of discos and we had a talent contest."
Cally, 13, Norfolk, England
"In 2007, me and about seven other people did a cot push across Douglas in our pyjamas! It took about an hour and a half to complete it all. The money went to the new children's hospice."
Katie, 10, UK
"At school we did a sponsored stay awake and stayed up all night in school. The money went to a small charity called Lights for Learning."
April, 12, Harrogate, England
"I did a sponsored walk for charity with my school. We did eight miles around Richmond Park. I love doing charity events."
Akalya, 12, London, England
"Our school is doing a sponsored walk around our local park. The entire school takes part and last year we raised over £12,000 pounds for charity!"
Bronte, 14, London, England
"My school does this talent show for teachers each year at lunchtime. It is £1 to get in and it is a real laugh!"
Paige, 12, Liverpool, England
"Our school all wore our jeans on a Friday, to raise money for 'Jeans for Genes Day.'"
Georgina, 11, London, England
"I've done a race for Comic Relief and on 31st of October I'm doing one for Cancer Research with my mum."
Charlotte, 10, Southampton, England
"I have just taken part in the Junior Great North Run for charity and have raised just over £100. I try to do a lot of things for charity even if I only raise a small amount because every little helps."
Rob, 12, Newcastle, England
"My cousin Megan and I did charity work for the NSPCC in our primary school."
Robin, 7, Belfast, Northern Ireland
"At the school I go to we have something called Charity Reps. Every so often they come up with ideas to raise money for lots of different charities. On Jeans for Genes day we all gave one pound to the charity for letting us wear jeans to school instead of uniform. And that's not all; at break some of the children made cakes and biscuits to sell and also guess the teddy and more stalls. We have made a LOT of money for charity over the years!!!!!!!!!!"
Eleanor, 12, Dorset, England
"A few weeks ago I did a sponsored run for leukaemia research at Willen Lake in Milton Keynes. Out of 400 kids I came seventh and I was the first girl. I also raised £100 for leukaemia research and most of all had great fun."
Anna, 10, Milton Keynes, England
"Every year our school does a sponsored silence for charity and this year we earned £170 but I can never manage to be quiet for more than one hour!"
Mica, 14, Liverpool, England
"Over the past four years I have done a 5 k run with my mum and my family. My dad did a 635 km bike ride from Berlin to Warsaw, raising over £3,500! I also take part in lots of charity fundraising at school. Having been born with a heart condition, I give lots of my old stuff to the British Heart Foundation and I might volunteer to help out."
Kate, 13, England
"My school had a dressing gown day and we raised £235!!!!"
John, 11, West Lothian, Scotland
"One day in school earlier in the year we did a sponsored silence. It was so hard to keep quiet - I don't know how I did it, lol."
Lyndsey, 12, Blackpool, England
"Me and my mates have been making bookmarks and selling them at our school. The money is going to three charities."
Holly, 9, Scotland
"I am running the 5k in Regent's Park next year with my mum, sister and my friend and her mum!"
Lottie, 13, England
"My PE teacher in school is running and we are all raising money for the NSPCC."
Emily, 13, Cardiff, Wales
"I've got severe asthma, which affects my life greatly. When I nearly died a few years ago, I became more determined than ever to help the fight against asthma. So I became a member of the charity, Asthma UK. I get a magazine four times a year and I am presently organising an event with my drama class to raise money for it."
Olivia, 12, Blackburn, England
"I have done lots of sponsored walks for charity."
Kim, 9, Edinburgh, England
"I try to do as much as I can for charity. I've done reading for charity, two sponsored silences, swims, walks, runs and also participated in a lot of school events to raise money. I really enjoy doing things for charity, and the fact that it helps other people makes it all the better."
Rosie, 13, Reading, England
"Me and my school ran four miles and raised £3,000."
Emma, 12, Belfast, Northern Ireland