I have no idea where I got this from, but when I was little I used to believe that this wasn't my real life I was living, but a dream life. I believed that I was actually still a newborn baby, and I was having this long, complex dream about my life to come. And that when I died in this dream life, I would wake up and my real life would begin. But everything would happen the same way, so in case I didn't like something, I would know about it happening ahead of time and I could change it.
A childhood belief about i'm different

others believed things like this
- I used to think that life was all a dream and one day i would wake up like a 75 year old woman.( who knows?)— 8 with wrinkles
- I thought that life is a dream and when you die you wake up (maybe it's true who knows?)— Naos
- I used to think life was a dream and I was in heavenAnon
- I used to believe that the last line of Row Row Row Your Boat was 'Life is butter dream'.— Mindless Misfit
- When I was little I believed when an actor died in a movie, he died in real life.— Ben
- I thought there was some video games so hard that if you died on them you also died in real life!— Kakuri