I ran 17 from the store this morning. I felt pretty terrible until the hour mark when we started to pick the pace up. I began to feel strong and pushed the pace after 75 minutes only to succumb to the sun's anvil when I left the comfort of the shade. Nice loop which I'll be sure to do again - north on the Towpath, over the Lock 5 Bridge, up Ernst Hill, down the Glover Arch trail, down through the zoo (where animals do their best to keep cool) and then south along Rock Creek Parkway until I hit the Towpath again.
I am going to amend my training plan just a little as I move into the summer. I'd like to attack my mile PR in about a month before moving up in distance. I will elaborate later.