Your motivator can even be something one wouldn't expect. For example, a time-conscious person might eat out less by reminding himself, "It will take less time for me to grab something at home."
Remember too that it takes 20 minutes for your brain to recognize you're no longer hungry. So eat little and move on to some other task, rather than eating until you no longer feel hungry, let alone feel full.
I suggest you tape a sign "STAY Conscious!" on your refrigerator and another one on your dashboard, to remind you when you're out. Read it aloud often to lock the concept into the forefront of your mind.
And if, despite staying conscious, you choose to eat something calorific, it's probably okay. You've made a conscious choice that, at that moment, the pleasure was worth the calories.
I'd love to know if this little post ends up helping you.