25-year-old Jamie Hall is running 62 miles from London to Brighton to raise funds for local youth charity SE1 United.
The London 2 Brighton Challenge takes place on 25 May.
"I ran my first marathon last year so am keen to up the ante and increase the challenge this year," said Jamie.
"I really respect that young people are in charge of how the charity is run. They are a serious group of people who are working hard to improve opportunities for themselves and other young people in their community."
If you would like to support Jamie in reaching his fundraising goal of £500 you can do so at his BT MyDonate web page.