How did you decide on your career?

I want to be a pediatric oncology nurse, but I get queasy every time I watch a nurse draw my blood. I wanted to be a wedding gown designer, but I don't want to have an extremely low income. I also thought about being a physical therapist that specializes in helping animals, not really humans. I love animals (especially cats) but I don't think I would like to see animals in medical emergencies, so I crossed out a vet. I have no clue on how to decide this and would just like some ideas on how to sort it all out. Thanks!