I personally cannot stand eating food if I'm about to engage in physical exercise, unless I'm legitimately seriously hungry. So if I have a random midday idea-of-food, I picture myself about to sprint to the nearest park, or about to swim a few km. Then I check my stomach again - how hungry is it now? I generally don't want anything at that point, but sometimes it does (begrudgingly) need fuel for the imagined activity - only then do I eat.