You’re right in the middle of a big project at work, something you need to get done today, but — oh no — you can feel yourself getting hungry. You can’t work like this. You need to eat. So what do you do: get a snack, or go out for a long lunch with co-workers?

Of course you get the snack. If you went out for the long lunch, your project wouldn’t get done. Also, the interruption would interfere with the flow of the work you were doing. After you return from lunch, you’d have to get back into …