Well, I did not plan on trying for a new 10K PR today, but after running the first three miles and being pleasantly surprised with my pace, I decided to go for it over the last 3 miles. It was grueling. I wanted to quit many times. My lungs hurt, my mind was strained from intense concentration, and my legs were starting to give up, but somehow I persevered. I hung on to the finish. My old 10K PR from last year was 49m 04s. I beat that by 45 seconds today.
My new 10K PR is 48m 19s (7:48/mile pace).