Where are you in school that you are considering this? The most important thing is, and I cannot stress this enough, is a solid mathematical foundation. High school physics and Physics 101 is solely rooted in algebra. To be a successful undergraduate Physics student you must be strong in calc 1, calc 2, and calc 3. These will be your best friends or worst enemies in your lower division courses. As you get further, ordinary/ partial differential equations and linear algebra will be the most important topics in your upper division courses. If you want to be a physicist because you think it is cool, you must extend beyond that and question whether you like these topics from a mind blowing/philosophical point of view or do you love the formulations of these ideas through applied mathematics.