As human beings, we get a dopamine rush from similar, promising surprises: the arrival of a sweet note from your lover (What will it say?), an email message from a friend you haven’t seen in years (What’s the news going to be?), or, if you’re looking for romance, meeting a fascinating new partner at a sticky table in the same old bar (What might happen?). But when these things become regular events, their novelty fades, and so does the dopamine rush—and a sweeter note or a longer email or a better table won’t bring it back.