What are the tactics you use to get through a long day at work?

I recently got a job at the local grocery store stocking shelves. Sometimes the eight, nine hour shifts really start to drag on. Lately I’ve discovered that avoiding looking at the clock at all costs helps to speed the passing of time. I’ve heard of other people who manage to zone out but still accomplish their tasks. I was wondering if anyone had things they did to make a long and painful day at work go by faster?