Whats interesting, at least to me, is that I had to struggle and force myself to run in the mornings in order to overcome that hurdle. Now, I find myself faster in the mornings. My 5-6 mile Tuesday night run is consistently my slowest pace throughout the week (well, except for those massive mile runs). But, if you take an equal number of miles and compare the times those mils are run in the evenings versus the times those are run in the mornings, I know that the morning times would average around 20 seconds/mile faster. Thats considerable!
Now, how I changed this, I have no idea....but its interesting to hypothesize. Any guessers out there?