The way out, the author says, is to have a trusted system for storing information outside your brain. In that trusted system, you can write down what needs to be done for each open loop, and that basically closes the loop for your brain and it will stop reminding you of that thing all the time.
I still haven’t gone fully into doing it but my director at work swore by it, and the few times I tried it it was almost like magic. Even if you just pull out a todo app or notebook and for each of the things currently looping in your head, write down only the next step you need to take regarding that open loop (and maybe what the desired outcome is - I can’t remember if that’s in the book or not). For me the first time I tried it it was magical - it turned out there were only 4 or 5 things total looping on my mind at the time and after doing this exercise my mind was basically blank - the reminder system stopped telling me there was something I needed to do for these loops.
I think for it to be sustainable you probably have to really make sure you follow up on the things you write down so that your brain actually trusts you’ll do the things you wrote down, but at least for me it worked really well as a short term hack on a few occasions. I really need to finish reading the book!