the parts of the brain corresponding to the limbic system (thought to respond only to more visceral, immediate rewards) were activated only when the decision involved comparing a reward today with one in the future. In contrast, the lateral prefrontal cortex (a more “calculating” part of the brain) responded with a similar intensity to all decisions, regardless of the timing of the options. Brains that work like this would produce a lot of failed good intentions. And indeed, we do see a lot of those, from New Year’s resolutions to gym memberships that lie unused.