Went out for 10 miles and quit after about 3.5 miles. The sun was hot which I am sure was most of the reason. It was 2:00 in the afternoon. It wasn't really hot at 81 or horribly humid at 72%.
I took plenty of water with me but didn't take any Gatorade because I only had one left and needed to save it for Sunday's 20+ miler.
I stopped for a brief second at about 3.5 miles and couldn't get myself going again. I walked/ran the 4.5 miles home.