Right, and your brain catches on to that "worst case", decides it is an existential or unacceptable threat, and dwells on it. Then your brain might think "Can't have that, those thoughts are unacceptable!" Which causes those thoughts to have more value, more attention, more substance, which in some people (OCD, GAD, panic disorder, agoraphobia) can trigger people to GET AWAY from the scary/unacceptable stimuli. Sometimes the stimuli is a thought itself! Uh oh, how can we avoid that? Enter compulsions (look away from child, step away, call spouse, call doctor, set knife down, yell, lay down, take medication, etc) that temporarily relive the fear/anxiety, but build into bigger patterns/habits (rituals). Enter repetitive counting, superstitious thoughts, repetitive sounds/movements, reassurance seeking from loved ones ("Is this ok?" "Am I ok?" "Is something wrong with me? Am I crazy?") which loved ones want to provide, because they don't want to see suffering. It's a tough cycle, but definitely can be interrupted at any point with a change in behaviors, change in patterns, recognition of patterns and acceptance of thoughts and feelings as just those, creations of a flawed nervous system that can go haywire fairly often!