10K for fun

I've really wanted to just get out and run, so that's what I did today.  With permission from my coach, I entered a local 10K, gave it everything I had and actually had a pretty good time.  I even managed to get 10th male overall and got a medal.  It wasn't my best 10K time ever, but it was yet another hilly course.  I wore my heart rate monitor but covered the heart rate reading.  I just tried to keep running as hard as I thought I could run.  I only looked at the heart rate results afterwards.  Typically, my lactate threshold is right around 166.  I hit 174 at the end of the first mile (a little downhill, and I did it in 6:40), and then maintained a heart rate between 172 and 176 the rest of the way.  My pace for the last five miles ranged from 7:20 to 7:35, but it seemed like it was either uphill or downhill.  I did pretty good going fast on the downhills and backing off the effort slightly and going hard on the uphills.  My average heart rate for the entire run was 172.  So, truly a lactate threshold workout.  My final time was 45:36, good for 10th male overall and 2nd in the 40-49 age group.  I'm still fighting some residual fatigue from the half ironman, but probably more so from work related stress.  Mentally, it felt really good to race.  This is my challenge right now.  I know that I'm mentally ready to get back into training, but I still feel like my body is trying to tell me something.  What it's trying to tell me I don't have a clue, as I tend to feel worse the less I do.  I'm supposed to alternate exercise with rest days this week before getting back into training.