Week 19: Down week?

What is it about the training, that 10 miles now seems like a 'down' week? How impressive is the human body, that by pushing yourself out of your comfort zone, you can make the body adapt in such a short time. I never though I would ever be saying 10 miles is easy (it was only a few weeks ago that running my first 'double digit' miles seemed like a huge achievement). But guess what, 10 miles now falls into the easy category.
I am done with the 10 miles. Can't believe it felt that simple..