I learned a lesson this morning. Yesterday I was late in getting to work, so I skipped breakfast. I went directly to a meeting, planning to eat afterwards. I became engrossed in revising my software per the decisions at the meeting, and I forgot about eating. I finally had a light supper about 7:30 pm. I also didn't drink much water during the day.
My wakeup HR was 55, and I felt pretty good when I got up. I ran my 6.4 miles and felt fine on the way out. In fact, I ran about a minute/mile faster than I did on Wednesday (I ran my "comfortable" pace, so the faster pace was due to my feeling stronger, not because I pushed myself to go faster). But, on the way back, I had no energy, and the last mile felt like the last mile of a marathon. So, it pays to eat well, because the energy I needed this morning should have come from my meals yesterday. I didn't eat much yesterday and didn't have much energy this morning. :(