It can be hard for me to get motivated to do speed work, so I typically drive over to Lazy 5 Ranch at night and jump the gate to run the road with all of the animals. Once you have a few of those things tailing you, it is pretty easy to keep 5 minute miles for the 5k loop. I have actually done it twice in one night, buying a Diet Mtn Dew at the vending machine in between intervals.
One of these days they are going to release the Rhino on me, although no one ever knows I am out there. My biggest fear are those huge yak things with the horns. Those and the pigs.