What else should I do to get into Princeton?

I'm starting grade 7 after summer ends and I've just realized that I haven't really done any extracurricular activities. I've just started fencing last month and I'm thinking about gymnastics since I'm naturally flexible (but I'm too old :/) or maybe cheerleading? I have one of the highest scores in my grade and learn very quickly. I am thinking about having a bachelor's degree in engineering physics and a phd in astrophysics or should i take physics as an undergraduate instead? But if I take engineering physics if my plans of becoming an astrophycist fails,I can probably get a decent job but I don't know what I would do if I don't get a job in astrophysics and only have bachelor's degree in physics :/