Overthinking isn't a failure of the mind. It's a sign that the mind has been asked for something it cannot give: certainty about what hasn't happened yet.
The Relief of Not Knowing is what remains as that demand for certainty recedes, revealing something steady beneath the thinking. A presence of mind that never depended on any outcome.
Written in second person. No acronyms. No twenty-one-day plans. No thought-stopping techniques. Roughly 28,000 words. Reads in an evening, sits with you longer.