Those medical school wannabes who avoid challenging themselves will be beat out by those students who can take the more difficult classes and still succeed in getting top grades. The top students will be taking more credits, more rigorous courses AND do well in them early on. There is no easing into medical school, best to be used to pushing yourself.
I was so fortunate I was taking courses for my chemistry major and others I wanted to then decided on medical school. I feel sorry for those whose only goal is medical school- so much more to college.