In the book, he notes the prevailing theory that our daily happenings remain on a sort of temporary scratchpad. As we sleep we sort, discard, process as necessary. Trauma however, is too big, too hard to process naturally. So, it stays on that daily scratch pad. Always with you. Every day, the same as if it were happening today. No relief, no dissipation of the emotional charge. Emdr therapy while walking to facilitate both hemispheres of your brain working together, is his prescription.
The book/methodology I can honestly say saved my life and gave me a life, a future. A way to cope with things that were driving me crazy. Everyone I've given a copy to has deeply thanked me later. Please, if you have anything weighing on you, give the book a look. It's only like 70 pages.