Most medical schools require a year, with laboratories, of biology, general chemistry, organic chemistry and physics.
Many schools also require a year of college English and college math.
While not required, courses in anatomy, physiology, genetics, embryology, biochemistry and the humanities are often strongly recommended. You will find many activities on campus that interest you. You may wish to form, or become part of, a good and serious study group. Three clubs that many premeds join are the Health Careers Club, AMSA Pre-Med Club and Tri Beta, the biological sciences honor society. Keep in mind that most medical schools prefer to see evidence of leadership and serious commitment to a few extracurricular activities rather than superficial participation in many.