You know how it is. You think of a scenario in your head. You think about how it might go. Perhaps you consider what you're going to say. Maybe, if you're crazy, you consider what the other person is going to say. You imagine all of this in your head. Maybe you do this, maybe you don't.
I do this most often when I'm thinking of how to say something in Spanish. I have some go-to phrases that I can whip out of my pocket and they just roll off my tongue. Other times, I have to think ahead of what I am going to say, or if I would say it one way in English, I try to think of another way to phrase it, using words I know in Spanish. When I don't plan ahead, I end up at the papeleria today, trying to explain to the lady that I would like a copy of a whole book, with covers, and bound, please. Yeah. Luckily she understand when I gripped the binding on the real book and made "chh chh" noises that I wanted binding on my copies. Genius.
So, it has become a habit in my every day life to plan ahead a lot of conversations. Except sometimes I go overboard. I find myself thinking of a scenario in my head, running through the whole situation, and then realize that the person I'll be talking to is American. Oh, Duh. I don't need to preplan that. That person and I speak the same language and I don't have to think about how I'm going to say anything. It will just come naturally.