A car alarm that goes off when a lorry passes isn't broken. It is set too sensitive, and it is doing precisely what it was built to do, far too often.
Fear that has turned into a habit works the same way. Somewhere back there it was calibrated by something real, and it has been firing at lorries ever since. Turning it down is a different project from switching it off, and a much more achievable one.
Pick one thing you brace for that has never once happened, and go a single day without the bracing. Not a cure. A recalibration.