Er, Lily, I think the main reason a horse is withdrawn is because it can't say, 'I want to run and its up to me!'
But seriously, no one forced her to run, she won't have had the local NHS doctors treating her and telling her she's fit to do it, she would have had world class docs, taking care of her.
I don't think any of us can, or ever will, understand the emotion, determination and drive that an athlete has. We're not taking about running the parents race at sports day here! Paula ran that race because she thought she was fit enough, her doctors told her she was fit enough and she did it to try and reach for her ultimate dream. Would none of you reach just that little bit further and harder to try to reach your dream?
In the end, she wasn't strong enough, but she came 23 out of the whole world, not last! Its not a bad acheivement. And incidentally, she is still world no 1 and fastest woman for the London Marathon. That'll be a handy bonus in 4 years time, won't it!