I used to be really, really scared of horror movies. To the point where I'd sleep with all the lights on and often cry. My parents loved them and kept trying to ease me in with the old, obviously fake ones or funny type ones.
I was really, really put off until I was about 13 or so and watched my dad's DVD of 13 Ghosts. I decided to watch all the "making of..." bits and once I saw how horror movies were made, they weren't scary to me anymore.
Now I love them and watch them all the time and actually enjoy them.
What used to scare you as a child and what helped you stop being scared?