When I was in my early teens, I firmly believed that good days and bad days alternated, i.e. I had a good day and a bad day and a good day and so on.
I used to wake up in dread of bad days and quite optimistic on good ones. I even noted it down in my dairy, to keep track. I believed this for years, till it just faded away.
A childhood belief about general

others believed things like this
- I believed if I prayed for the Devil, he would start being good for God. — Jackie
- I'm deaf in one ear. Until I was 7 I believed that if I didn't sleep on my good ear, dinosaurs would eat me.Anon
- My Mother used to tell me only the good die young and I would live to be 100+ years old because I was bad.— William
- When I was 6 I believed that on nice summer days you can see the world spin if you just look hard enough :)Anon
- When I was little I used to believe everything the government does is right and for the good of everyone.— Rob
- I used to think the olden days came once every couple of yearsAnon