Dave Kashen uses the fisherman metaphor to explain how your mind works: intrusive thoughts are bait, and you don't have to take them. The practice is noticing when you've been hooked and returning your attention to what's actually happening right now.
Chapters
I've been using this metaphor recently of the mind as a fisherman. So if you think of your mind as this really talented fisherman and it's particularly talented in the species of fish called you, in that it knows just what bait to use. So you're this happy little fish swimming along in the present, and then it just drops this juicy bait. Uh-oh. What if this bad thing happens? Ooh, that last meeting you had, you should have said this or that. Oh, you're not good enough. And it just catches your attention. And now your attention is off focusing on these things that your mind is saying. So what I love about this metaphor is your job as the fish is two things. One, learn to snot take the bait, right? If you're present and the mind drops one of these juicy baits, thoughts, just don't give it attention and just stay in the present. Or if you've noticed you've taken the bait and now your attention is hooked, simply open your mouth and return to the sea of presence.