Hello Rachel: Here are a few links to help you with extracurricular activities that medical schools look for. Some of these areas you may want to start participating in while in high school and then in college.
*Community Service / Volunteerism
FYI, my son is a second year Pediatrician resident. Believe it or not, he did participate in these kinds of activities and more (ie, traveled abroad, mission trips, etc). At his high school, they offered a Medical Explorers Program, which he got accepted into. Each month he and a team of Explorers would visit the local hospital and shadow doctors for approximately two (2) hours making rounds to all areas of the hospital for that session. In college, he did research with a Professor in the lab. . .
You can do this by researching the resources to help assist you. Start by checking with your Guidance Counselor, Church Youth department, etc. Your time is precious so please choose your activities wisely and make it count. :)
Good Luck to You!