Have you ever seen something or someone that you think would give you personal happiness or fulfillment? You go for it with everything you have, and then it's gone. You are left to wonder why you're still empty - looking for the next thing to come along.
Maybe you haven't gotten what you've been pursuing, whether it's a relationship, an accomplishment, or a position. You feel you have an incurable restlessness. If you've gotten what you thought would fill the hole in your heart, and the hole is still there, your next stop is despair.