Thousands of people are getting ready to take part in the London Marathon this weekend, and you might recognise one of them. Former Newsround presenter Martin Dougan will be taking part in the famous 26.2 mile race in his wheelchair. He will be raising money for the children's mobility charity Whizz Kidz. Martin was a Newsround presenter for nine years and was also captain of Scotland's Wheelchair Basketball team. He was born with cerebral palsy and became a full-time wheelchair user at the age of 13. Martin wants to help children get the right wheelchair sooner, so they can experience what he did when he was younger.