Something I used to wonder quite a bit, and only remember it now because my writeup count has just rolled over to
666.
See, back when I was a kid in the 1970s there was this movie called The Omen about this other kid - not me - named Damien Thorne who was destined to grow up to become the Antichrist. This really stuck in my head for some reason, probably because I was a fairly imaginative and somewhat paranoid little boy. What if, I wondered, I was the antichrist? I didn't think I was, but how would I really know? If I did turn out to be the antichrist, was there any way out of it? Or are we all just pawns in the hands of Fate?
This bizarre obsession was eventually displaced by "What If I'm Really Forty Years Old And In A Madhouse, Reliving My Entire Life Over Again In My Head?".