Run "Fast" for a mile (think 5K pace), being careful not to go out too fast and burn out. Walk a quarter mile. Run "Fast" for a quarter mile trying to duplicate the pace from the first mile. Walk a quarter mile. Run "FastFast" for the final quarter mile.
Not bad! First mile average was 9:56min/mi, and I did a reasonable job guarding against going out too fast. First quarter mile was 9:49 - pretty good pace match. Final quarter mile was 8:38. For me, that is really good.
(Note: Pay no attention to that little leftover .01 mile, I just didn't hit my stop button on time!!)
I have done a lot of long slow runs and hadn't done anything resembling speedwork for months. I wanted to reassure myself that I can, in fact, pull off something faster than an 11:30 if I really try. I also wanted to see if I could replicate a pace by feel. Finally, I wanted to see how fast I could run (all out) for a short distance.
I think it was a success. I might try this again in a few weeks.