A tough run, but, for the most part, pretty well executed. 2 mile warm up was strong and steady. Picked up the effort slowly over the next mile to "marathon effort" & maintained that effort for the next four miles. At mile seven, increased the effort and pace slightly to just a bit faster than "marathon pace" and was able to maintain that increased effort for the next two miles. Returned to "marathon effort" for mile 9, but started to struggle with that pace/effort about half way into the final two mile segment at "marathon effort". With about a half mile to go in that final segment, I had to ease off as I started to feel a little light headed, probably a combination of the stronger sun & a little dehydration. Took a breather at the end of the tenth mile to reset myself & then finished the cool down mile at very easy effort with no recurrence of the lightheadedness I'd experience at the end of mile 10. Completed full set of exercise routines after the run.