Of course it's about running.

So that 28:38 is old news now. Since then I've run 27:34 and 28:22 for the same distance. I'll improve gradually, then I'll plateau for a while, then suddenly a sizeable gain in just a few days, then that low time becomes the new plateau. For example, before two weeks ago I had only broken 30 minutes (for 3.75 miles) once, and now not only have I done it three times since, but last night I felt like I was doing very poorly - poor form, puffing, not enough water that day - and still ran 28:22. So the lesson I've learned is to just keep at it and the gains will come.

Now as my training program starts increasing the distance, at least on the weekends, I'll try to make the same sort of gains on long runs, and what's fast for a 12 miler now will be slow by September.