So glad to know that others thoughts are similar to mine!
First 5 minutes: Ugh, why am I doing this? Why does my ass have to jiggle so much? Oh, yeah, THAT's why I'm doing this.
Next 15-20 minutes: Listening to music, in the groove, and either working through some problem/issue with work, thinking about my running/weight loss goals, or thinking about sex.
Last 5-10 minutes: Watching the time and just trying to finish the run.