During the night my nose started to drip and I coughed up a small amount of phlegm. In addition, my wakeup HR is back to 55. I thus decided to take a rest day. When I was younger I would run through colds, but at my age, I have to give my body more rest to help it recover from colds. Resting today will give me a better chance of running all four days next week.
I had planned on running an hour of fartleks today, but the temperature this morning is 10 (F), and I'm not sure I want to do speed in cold weather. So, if I were to run this morning, I probably would have done an easy rest-run.