I am not in the medical field but I had several friends in college who had a passion for this field. I noticed that those really passionate about finding a career there got involved early on and any way they could. I would say try to volunteer somewhere in the medical field. Even if you cannot find a position in the specific area you want a career in, it is better to show initiative and have experience.
I had several friends that worked at nurses stations in hospitals. While their work they did was not what they wanted to do in the future, it got them in the environment where they could watch and learn. This also allowed them to network with all different kinds of medical professionals and create connections. I had one friend who volunteered in a cancer support home for women. She met many people through that position and it helped her find her true passion.
I would suggest looking for volunteer roles in your community that get you in to the medical field environment early so you ca start making those connections that will be valuable later on in life.
Best of luck to you!