Even though I had 7 hours sleep last night and my wakeup heart rate dropped two points to 51, my energy level was low this morning. My plan was to run a mile to warm up and then do a few cadence drills, but my energy level was so low it was as if I never warmed up. The result was that I did no drills. I had a good run on Monday and ran about a minute per mile faster, and apparently one day of rest wasn't enough. Today I did jog the 4 miles but with a lot of walking. My next run is planned for Friday and if I feel fine, I'll do a few cadence drills followed by a few fartleks. If I still feel tired, I'll abort the run.
One thing that may have contributed a little bit to my tiredness was that I wore my thick, long sleeved cotton T-shirt. When I first got up, it looked cloudy and cold outside. Later, when I dressed for running I put on the thick shirt. After I started running I realized I should have worn a thin, summer shirt.