Why we love to run

It's tough, it hurts and yet more than two million of us in the UK run at least once a week. Why? To launch our new running blog, Adharanand Finn explains the enormous pleasure it brings and how we're actually hardwired to do it

"Daddy, where are you going?" my son asked me recently as I was lacing up my running shoes on a cold, wet Sunday morning. "Running," I said. "Why?" he asked.

He's only three. But it was a good question, and one I couldn't readily answer. I...