Brave enough to enter

I'm watching the London Marathon with a slightly morbid thought, will we have a repeat of the Boston bombing.
The London event has picked a delightful day with the sun out.
It is truly amazing to see the massed runners waiting at the start of the event, a sea of humanity, shuffling forward slowly to cross the start line, as they do so, their timing chips activated, their race begins.
Why do people punish themselves in this way, what is it in the human physic that seems to enjoy the call of the herd. They have no chance of winning of course, the men and women who do, belong to a different universe they aren't really human. They come from countries that in other respects are way behind but in long distance running they are superstars.
So why do Mr and Mrs Bloggs set off to punish themselves in this way. The camaraderie, the knowledge that "taking part" is one of the most important stimuli for humans. To have a sense of their individual importance in the wider scheme of things, in a world in which we are often made to feel inconsequential. Weeks of pounding the streets with club mates come together with other runners from all parts of the UK. It becomes a club run of gigantic proportions. The support from the runners around when as you hit the wall, the collegiate spirit established through humour as well as grim pathos.        
The Olympics were a revelation. The self imposed restraint that dictates the English blew away.  When I hear recordings of the Games, the sound of the crowd, is a spine tingling emotion. It was unimaginable to hear the near hysteria of the people cheering the athletes on. Today the crowds were out again, clapping and cheering all around, lining the streets, acknowleging the people who have been brave enough to enter.