I usually think of a place that I know has good food, but that I haven't been to in a while. That way, I'm sure to be able to find something that I like, while at the same time not getting bored of eating the same things everyday!
I work within walking distance of an open air mall so there are lots of places to eat. I usually cycle through the ones worth eating at over the course of two weeks. Today, for some reason, none of them appealed over any of the others.