First six miles were excellent. First four miles would appear to be a bit too fast, but these miles were decidely downhill. About half way through mile 4 the course flattened out & the pace "slowed" to 9:03-9:04 for the next 2 miles, which were run at pretty much the same effort as the earlier "faster" miles. The next 3 miles were on the Indy Motor Speedway & were a logistic nightmare. The running path was fairly narrow & hundreds of slower runners were strung out on the track. As a result, there was lots of slowing down & side to side movement to find space to get around the slower runners, which not only slowed me down, but unnecessarily expended lots of energy. And, of course, it made it impossible to maintain or regain the nice running rhythm I had coming into the Speedway. In miles 10 and 11, I was able to get my pace back down near my target, but also began experiencing some discomfort in my legs, probably a combination of the warming temps, the strong sun, & the extra energy expended on the Speedway. With the discomfort came the usual negative messages from my brain. Unfortunately, in miles 12 and 13 I gave in to the negative messages and took 3 short (20-30 second) walks. After looking at my Garmin Connect stats, the affect of this "discomfort" on pace and cadence was really miminal & taking those short walks turned out to be a poor running decision that cost me another significant chunk of time.