There's biology and there's biomedical engineering and there's medical professionals.
if you like scientific research then you can major in biology and get a Bachelors or graduate degree and do biological research on things like cures/vaccines/more target chemotherapeutic drugs with less harmful side effects/research artificial limbs that can connect to the brain that allow them to be controlled, etc.
you can get a ph.d and become a professor.
you can major in premed and become a doctor.
you can get a Bachelors in Nursing and be a RN that works in hospitals using biology to improve patient's lives.
You can become a pharmacist that researches drugs that fight cardiac disease.
If you like advanced math you can major in biomedical engineering and work on applied sciences like things including developing the newest generation of medical imaging equipment (MRI machines, ultrasounds, positron emission technologies, etc.)
Biology is a growing field that will always be in demand since it ties strongly to improving human life. Do some research in current news and Wikipedia on biology related stories/articles to find what you are MOST passionate about and pick a major/career from there. I picked biomedical engineering with cancer research but there are many many expertises out there.