1. Think about what I have to do after I finish running
2. Mentally sing / shout / scream along with whatever music is playing on the iPod, also try to avoid air-guitaring along with solos lest I look even stranger than usual
3. If spotting a reasonably-to-very attractive woman also running, wonder how best to introduce myself to her. This happens more frequently in late spring - early autumn.
4. Watch out for the idiotic drivers who seem to infest my normal running routes and have a tendency to not notice I'm there (usually because they're too busy chatting / texting on their fucking cell phones while driving)