Trying to decide what I want to do in life

I’m almost 29 years old and I’ve been working crappy jobs all my life. I majored in accounting and I’ve considered going back to get more schooling. But I’m not sure it’s what I want to do. I’ve always been heavily interested in the human body. Diseases/sicknesses/trauma. All of how it impacts the body. I don’t want to spend so long trying to become a doctor or something but I guess I’m wondering what would be a good field for me to go into. I just want to actually do something and unfortunately I wasted my 20s not figuring it out.