Cognitive fusion isn’t necessarily a bad thing. If you suddenly notice a car driving towards you at a high speed, you don’t want to get stuck pondering about how the feeling of danger is actually a mental construct produced by your brain. You want to get out of the way as fast as possible, with minimal mental clutter interfering with your actions. Likewise, if you are doing programming or math, you want to become at least partially fused together with your understanding of the domain, taking its axioms as objective facts so that you can focus on figuring out how to work with those axioms and get your desired results.