I had a rather rough start when I had a bad experience riding Space Mountain at Disneyworld as a kid. For the next 20 years I only rode a few coasters here and there, and mostly only if I was asked to accompany someone. In those days coasters (anything bigger than a boardwalk or fairground coaster) were scary and I white-knuckled my way thru them. But I somehow became deathly afraid of coasters with inversions, and I wouldn't even go to a park unless someone invited me. And then I avoided looping/inverted coasters at all costs. Well, one day when I was in my mid-20's, I did get an invitation. A family friend invited me and my mom to go with her and her family as guests at a company picnic at a nearby park (what is now Six Flags America).
I had no idea what sorts of coasters they had, but I planned on making a point to avoid them if I could. At that time they had one wooden coaster, which I reluctantly rode and was glad when we got off. There were two coasters with inversions, one of which I was glad to discover it was closed for the day. But the other one was running, and it was this one that I got dragged onto. I tried to get out of it but my riding companions for the day would not take no for an answer. It was that, or be forever branded as a chicken... I was scared half to death but I chose the coaster, figuring I'd only have to ride it once to prove myself and I could hopefully deal with a minute and a half of terror. Well, I rode it, and I thought for sure I was going to die right after the first drop. I was so glad when it ended, and glad that the park had no more coasters.
But a strange thing happened the next day - I had a strong desire to go back to that park and ride that coaster (and the other two) again. So I had a friend who liked coasters and we spent the rest of the summer into the fall revisiting that park and a couple of other area parks and rode as many coasters as I could. That was back in the mid 90's and I've been riding ever since, and have ridden over 275 coasters. So somehow I was a phobic who got turned into a fanatic...my mom still blames that friend for turning me into a coaster enthusiast!