I didn't run on Monday because I didn't sleep very well and was tired. Today, however, is different! I had a great 8 mile run today. My wakeup HR was 52, and I felt great when I left, during the run, and after I returned. I've done the 8 mile run probably a dozen times since last Fall, and I'm getting used to it. I'll be glad when I feel that way about my 15 mile long run; I should be adjusted to the 15 miler before my next birthday in October.
I don't know what the stress was that interfered with my sleep Sunday night. Monday night was a bit better, and last night was pretty good. A lack of sleep really affects me.