We typically have little control over our thoughts, but we often invest them with a lot of authority—even when they contradict what our experiences tell us to be true. Take a moment right now and think There's a hungry grizzly bear sitting next to me. Chances are you didn't take that thought literally and run screaming from the room. But what if instead you had thought, *I'll never get a better job,* I'm boring, or No one loves me? Just like that terrifying grizzly, these more garden-variety thoughts are just words and pictures that pop into our minds. But often we take thoughts like these literally and let them trick us into avoiding the lives we really want to live. Leave Your Mind Behind offers a collection of light-hearted practices readers can use to learn to observe their thoughts without getting caught up in them. Each practice is grounded in a component of the new acceptance and commitment therapy (ACT) called cognitive defusion: the process of de-fusing or not identifying or becoming one with your thoughts. Sometimes downright strange—imagine yourself hearing your thoughts in the voice of a headless monster!—these activities don't seek to stop or control problematic thinking. Instead, they work to show readers how to observe thoughts without judgment and learn to live with the confounding and marvellous word-making, story-telling machine that is the human mind.