Going Out Too Hard

I took the afternoon off of work to do my key workout #1 for week 10. It was 2×4 miles at MP with half mile recovery between intervals. I started out with a 2 mile warm-up then headed to the park. I kept the pace between 7:45 and 8:00 min pace, trying to improve on my fitness level. It was hard, but comfortable. I took a little longer recovery, knowing the the next interval would be tough. I started out at the same pace. The hills on washington were taking their toll. With a mile to go, my knee was acting up, and I took a walk break and took it easy the rest of the way.