I don't know what to be when I become an adult?

I am a sopre in High School. College will soon be around the corner before I know it. Ever since I could remember, I never knew what I wanted to be when I grew up and I still don't. It frustrates me how there is not anything that I am necessarily pionate about. I love little things about a lot of jobs. Especially rewarding ones. And some of the jobs that I have considered like an obstetrician or an oncology nurse seem to take many years to become. 8+ years is a lot of years of schooling. It is not just something that you "give a try." People are pionate about it. And considering something is definitely not the same as being pionate about it.