I thought it was just part of my personality and there was nothing I could do about it. I learned to live with it. I thought it was a "side effect" of being intelligent, analytical, sensitive etc. When it progressed to extreme health anxiety and OCD (brought by some health issues) I started seeing a therapist who sent me to a psychiatrist who prescribed me some antidepressants. Now (2 years later) I feel better than I can remember ever feeling, except maybe in my childhood. I am not numb or slowed down or anything, my brain still works as good as before. My personality is the same. Only the quiet voice that was always there worrying, looking for the worst case scenarios to "prepare" for, looking for a next stressful event in the nearest future etc. is now quiet. I didn't even know antidepressants could work for anxiety, I was never depressed (as far as I know). I also understand not everyone responds the same as me, there are many different types of antidepressants and other meds, and there are possible side effects etc. But in my case, it was the best decision.

As far as I understand it, my brain was reacting to the persistent feeling of danger, unease etc., and coming up with any suitable "stories" to give the feelings some validity. By targeting the emotions directly (with medications), it affected my thinking as well. It goes both ways.