I remember being in Hollywood at the age of 16 and marveling at the stars. The idea of being part of it never entered my mind. It was too far-fetched.
Depending on what your interest in theater is, I always recommend working on plays. It's a great way to be introduced to the field, and also a great way to be seen by agents and representation. I'm also a great advocate for studying acting at a drama school or a college.