A veterinary ophthalmologist.
I know. Specific, right? You see, my grandmother got a collie when I was a kid, and collies are prone to a variety of medical conditions, one of which is eye problems. It had never occurred to my adolescent mind that animals might have problems with their eyes the way humans did, and from that moment on… I wanted to be an eye doctor for animals.
I grew out of it, as kids usually do. By the time I hit high school, I wanted to be a music teacher. That didn’t pan out either, but I’m happy where I ended up.