You may already have heard of Claire Squires, who collapsed and died whilst running the London Marathon.
She was running for the Samaritans, and wrote on her JustGiving page:
"hi guys as you all know i am running the london marathon it was just going to be for fun. but its a fab opportunity to raise money for my charity the samaritans if everyone i know could donate £5.00 that would be a great help and change lives."
So very sad.
If you can, please pop over to her JustGiving page and sponsor her whatever you can afford.