You don't "feel" the difference?
It's a tough one when you enjoy running long distances. You'd have to pay me for that and I'd probably still fight it. Mark has some articles about it, somebody will probably post but in the mean-time do a little searching through the blog. I actually never bothered to read in depth about it since it's not something I do. All I read was "don't run so often" and went "fine by me!"