Philosophically speaking, Is fear even real? Can you conquer it?

I was lying in bed and delving into my imagination. I started thinking of the worst thing imaginable that could happen, right there, in the moment. I literally got scared for a second. My heart started racing and then all of a sudden I changed my thought process and my heart slowed down. I basically conquered my fear through an altered perception. Then I started to wonder if you could actually do this in real life situation. If fear is just a perception we have of something then can’t we change our perceptions and lose our fear? Can we train ourselves to accept death in the eye of fate and calmly kick the bucket?
I didn’t completely change my focus. I was still thinking about it, but it a different way. Instead of being scared of it I accepted it. Then I basically thought about it without being scared of it the next time.
I beg to differ, fear can kill you. If you fell through the ice, your first instinct is to panic and squirm and flail, consequently wasting your energy and losing any change of actually surviving your impending doom. Take someone who has conquered fear. They fall through the ice, alter their perception of what is going on and start thinking critically on what to do to survive. Fear distorts your rationality.