I ran 4 miles this morning but was getting tired

I was out 2 1/2 hours earlier this morning, and it was nice to run in cooler temps. The shade temperature was in the mid 70s (F) when I left home and in the mid 80s when I returned. Right now the shade temperature is 97.

My wakeup heart rate was 55. It appears that my body is going through the same reaction to the chemotherapy cream that I had last week. Today is day 3 of the 5 days of treatment for this week. I felt pretty good this morning when I first got up, but as I ran I could tell I was getting tired, and at the 2 mile mark I felt about the same "tiredness" that I felt last Thursday at the 1 1/4 mile mark. I thus turned around and headed back. Before I left home, I filled four 8-ounce bottles with water, but I forgot to take them. I thus ran the four miles with no water. However, thanks to the cooler temperature, I didn't need water as much, and I think the two glasses of water that I drank before I left home was enough. This week I was out earlier and ran in cooler temperatures, while last week I had been on my feet for two hours in the morning at the Pioneer Days parade in Salt Lake City. So, I'm not surprised that I ran farther this week.

I just woke up from an hour nap, and I feel more tired than when I went to bed an hour ago. I'll see how I feel tonight and tomorrow.