Long run ideas...anybody??

I run my long runs on Saturday morning. It can take me several hours or more, depending on the distance. This gives me alot of time to think....too much time. I dont like to carry any music since I run on the streets. I need ideas of things to think about while I'm out there. I usually get caught up in my time and then do these elaborate math problems in my head figuring exactly when I should reach a certain point at a specific pace. This can be rather draining. So come on people!! Get inventive here...something that will involve thought, but not put me in a bad mood.

I have been told to pray for a specific person at each mile. Thats a great idea, except I dont know 15 people that I would want to pray for. You can call me cynical if you want, but at least I speak the truth. So all your ideas would be appreciated.