The part of the human brain responsible for avoiding loss and staying safe is considerably larger than the part of the brain responsible for logic. You end up making decisions based on fear and rationalizing those decisions with logic. This attribute is excellent for animistic survival. It's kept the human race from going extinct.
It also keeps people from doing things they may end up loving.
The first time I had to give a speech was in speech class in my freshman year of college. I froze on the practice run, and never returned to class.
The second time I gave a speech was only for five people and video camera on a mentoring retreat. I froze and could not speak.
The third time I gave a speech was in front of a room of over 100 people at breakout session for my one of my industry's most prominent conferences. I have never felt more alive in my life.
I wasn't any less scared the third time I gave a speech than I had been the two previous times. The difference is the third time I chose to do it.
I would have missed the opportunity to discover this passion had I allowed my fear of past failures to keep me from trying again.
Do scary things. You never know what you may learn about yourself.