When I was in the city last weekend, I
felt healthier because we were walking everywhere. Of course, considering how hot and smoggy it was, I was probably inhaling all manner of toxic things.
...But yay for walking!
"'But do you really mean, sir,' said Peter, 'that there could be other worlds --all over the place, just round the corner-- like that?'
'Nothing is more probable,' said the Professor..."
-The Lion, the Witch, and the Wardrobe