I try to listen to my body and adjust my training accordingly, but I missed one message from my body that I was tired from my training and needed to take a break.
The message that I missed was a decreased enthusiasm for training. I was lethargic about non-running tasks that I needed to get done. Being retired, I have a lot of time to do yard work, house repairs, etc., and usually I have a lot of energy and interest in doing those things (once I quit procrastinating and get busy with the tasks, that is). Towards the end of last week I just moped around and didn't get much done. I went out running but didn't have the excitement that I usually have for the running. I recognized that I wasn't getting much done around the house and yard, and I told myself that I needed to buckle down and get busy. Of course, doing that would just make things worse.
Fortunately, I realized on Saturday that my real problem was that I needed a rest from the intensive training I was doing. I was overtraining. So, this week I'm running fewer miles. In the future, I will follow the suggestion from Jeff Galloway and have a "rest week" of reduced mileage once a month.
Here is the link to the page in my running site on Overtraining.