I had a number of odd experiences growing up but dismissed them as coincidence or imagination. My Mom used to tell me stories of things I did as a toddler that sounded more like an X-Men comic (telekinesis, ESP, clairvoyance, ect) but I never believed it, I figured she was just making stuff in a weird, failed attempt to humor me. One time she even got my sister in on the joke as they both insisted that an odd blue light had visited me while I was asleep. It never made sense to me because stuff like that was so obviously make believe that my Mom and sister acting like it was real left me very annoyed.
It wasn't until I was in high-school when I actually experienced something that made me question my stance on all this stuff, and even then it took a couple of years for me to actually accept it and I still hold a great deal of skepticism even to this day. On that bright, sunny day that was otherwise warm and pleasant I saw an entity that I have since heard called a "Glimmering Man". I had never seen or even heard of such a thing existing but there it was right outside my window. It then came into my house and started to move various items around and arrange them in circles. I had no explanation for what was happening, I kept trying to convince myself that it was something normal, like the idiot crackhead neighbor has broken into the house and was moving things. I even went so far as grabbing the phone to call the cops, but I didn't know what to tell them. I couldn't really wrap my head around a supernatural explanation because I knew that it wasn't scientifically possible, but I couldn't deny what I witnessed first hand. Those levels of cognitive dissonance plagued me for years as I tried to rationalize what happened.
It didn't help that when I started to seek out people who believed in all this stuff and would tell them my story the tables would turn and they would all look at me like I was crazy because nobody had ever even heard of someone experiencing what I did. Like my story was somehow too fantastic to be real.