Back from the lake and my back is killing me.

We went out to Lost Lake yesterday and it was a fantastic day. We had a little picnic lunch when we arrived, then rented a rowboat, spent about two hours gliding along the lake and just enjoying the nice weather. Matt rowed most of the time (he's much more coordinated than I am and had been using the rowing machine at the gym so he's had more practice) but for the 15 or 20 minutes that I rowed, I felt like I was doing it wrong. And boy was I right. Today I have a stabbing pain between my shoulder blades and my spine that goes up to my neck. I am such a wuss.