I added a quarter mile to my run, and I continued the longer running that I did on Saturday. A cold front is going through Utah, and the temperatures are significantly cooler than they were on Saturday. The shade temperature during my run was in the low 60s (F). Also, I was out earlier (10 am), and there was a lot of shade on the Parkway path. I felt fine going out but started to get tired on the way back. It wasn't a good idea to increase both my distance and longer runs. Doing that meant that my body had an increase in stress from two sources (greater distance and longer running of each segment) rather than from one source.
Thanks to the Labor Day holiday, there were a lot of people, mostly cyclists, on the Parkway. It was a beautiful Fall day -- lots of sun and lots of clouds.