Do not slack off. You can shorten your time earning an undergraduate degree by taking AP science classes in high school. Generally, those wanting to enter medical school after college major in biology, physics, chemistry, or specialized pre-health sciences.
Most medical schools require a 3.6 or higher GPA. In addition, medical students need stellar scores on their MCATs (Medical College Admissions Test scores).
During medical school, you can rotate through different specialties to see what you like. After medical school, students are required to spend one year in a residency program before moving on to a neurosurgeon residency program. Residency programs give you a chance to see what it's like for a life full of long, 10- to 12-hour workdays. Don't forget night calls and weekend calls.