More Humidity?

Another so-so run today that I thought would go better. The temperature was 73 degrees but I still never felt great. I thought it might be humidity again but upon further review it wasn't hat bad. Maybe I'm just having a tough time getting things going again after being on vacation. I felt the urge to walk at one point but finished the 6 miles without doing so. The clouds were out for part of the run as well so don't know what the problem was today. We'll see how Saturday's run goes and if it's any better.