Want to understand how nature and her underlying mathematical framework work? Then Theoretical Physics is for you. I assume a decent background in high school mathematics (namely Algebra, Geometry, Trigonometry). A basic course in high school physics is helpful, but not a requirement.
Please note that aside from reading books, the key element of your success will lie in problem solving. Solve as many problems as you can, for it is through solving problems that you really learn the material.
Enjoy your voyage of discovery. It won't be easy, but it will be worth it. Remember, "Without labor, nothing prospers."