My wakeup heart rate this morning was 49, and I felt great. Because of my low heart rate and my feeling good, I considered running 8 miles today. I didn't run until late afternoon, and I felt great during the 1.5 mile out-back on the new northbound leg of the path. But, after I had gone another half mile I could tell this wasn't the day to increase my distance, and I settled for a rest run. I ran a slow pace and felt OK during the 5 miles, but by the time I finished the 5 miles, the sun was down and the temperature was dropping. I wore a long-sleeved cotton T-shirt (one layer), and it was damp from my sweat. As the temperature dropped, I started to feel cold, and I was glad to stop at 5 miles. The temperature was in the high 40s (F) when I left home and was probably close to 40 when I returned home.