Training - Painful?

The day after my competitve training run was my actual speedwork day.  I had a 5 mile tempo run with 3 miles at half marathon pace (9:09 minute miles).  I'd decided to do this one after work and where I work as it is the flattest area of those I run on.  I headed out of the office at 4:15 and set out.  I'd typically go right as it's less traveled, but the road was closed so I had to head left.  I seriously considered just calling it because I HATE running where/when I'll look like I'm trying to be seen and I knew that a lot of folks would be leaving work at 4:30 or 5:00 and they'd all be passing by me.  But I decided to stick to it rather than sacrificing my goal of completing my workouts for a trivial reason when I was doing so good.  (This was the last week of September and I literally wrapped September up with only 2 missed workouts all month!)  I did my first "easy" mile to warm up...my target pace was 10:30mm...I glanced at the Garmin .6 miles in and realized I was hitting 9:28mm...I wasn't stressed over that because they still felt easy.  I actually was happy that I was apparently in better shape than I thought.  The Garmin beeped one mile and I picked up the pace, targeting 9:09mm.  I felt like I was hitting my pace and I'm typically careful to try and run by feel vs. gadgets, so I waited a while to check the watch.  .68 miles in I realized I was running 8:08s.  Not good...I knew I'd burn out long before 3 miles at this rate.  (I'm not a fast runner, I'm a distance runner.  I'd like to be faster and I know to get faster I need to run faster, but my goal right now is getting through the distance of all the doubles, not increasing my speed.  I'm work towards that later.)  I tried to back it off a bit.  I waited a while before checking the Garmin again...1.34 miles and I was holding an 8:37mm pace...ugh...no wonder I was starting to feel this.  I tried to back off a little more...after my turn around point I checked the Garmin again...8:42mm.  I was wearing down quickly and there wasn't much need to "try" to back it down, my body was doing that on it's own.  As I started heading back towards the office, as predicted, the flow of traffic from folks leaving was pretty heavy.  I tried to avoid eye contact with folks and just stayed focused on my run.  I was fine physically, legs were good, lungs were good, heart was thumping along strongly...but my head was playing games with me.  I was having a hard time keeping my pace because I KNEW I'd gone out too fast so I THOUGHT I should be more tired than I was.  With half a mile of speed left my legs were beginning to slow and I felt like I was running through waist deep water.  My boss and his boss's boss both passed me on their way out for the day (one is a biker/part time runner and the other a tri-athlete), I nodded but thought they didn't even see me.  A final glance at the Garmin told me I was holding 9:12mms, not too far below what I was supposed to given how fast I'd gone out, I was ok with that.  The final mile beeped in and I slowed my pace to recover.  This was the only mile I actually hit my target on and I only kept that target for about a quarter of a mile and then picked the pace up again, though it still felt easy so again I was ok with it.  The next morning my boss let me know that the two of them were actually on their way to meet up for a bike ride...where they both agreed I looked like I was in pain when they passed me.  Honestly it wasn't a physically painful run, but it was sure mentally painful.