I was not much of a worrier in childhood; I was the opposite, and I often sneered at the worries of my younger brother, of which he had many. On a plane, a nearby passenger asked him to stop talking about all the things that might go wrong, because he was making her nervous.
I didn't worry about things, but I got angry about injustices a lot as a child, some of which had no bearing on me. With reading fiction, I knew (with pride) that it was fantasy, so I didn't worry about things in books really happening to me. I remember being made to watch the news regularly before starting secondary school, and I noticed how full of terrible things it was; again, I got angry about them, but didn't often worry about them happening to me.
However, I did have certain individual worries. I used to worry about being sent to prison. When I read Jacob Two-Two meets the Hooded Fang aged 7, I knew it was fiction, and really exaggerated, but I was able to imagine a "children's prison" after reading it. We saw a stage play of it as well.
@KeeleyJ At my school, they sat us down to tell us that the Gulf War was not going to be a war like we learned about with WW2, and the horrors that went with it. I was 11 at the time.