Get into a line that you will find to be a deep personal interest, something you really enjoy spending twelve to fifteen hours a day working at, and the rest of the time thinking about. ↗
I have many times thought I did the wrong thing, but the reason was not to be a medical doctor - it was just to have the information. But then, maybe I was wrong, I don't know. ↗
There is a new way with very very tiny fiber optics, which give an enormous high resolution. There are many many thousand fibers, very very close together with a very small diameter. ↗