Analyzing and writing music aren't the only things you can do with music theory. For me the main application at first was playing music by ear. For example, you

Analyzing and writing music aren't the only things you can do with music theory. For me the main application at first was playing music by ear. For example, you could learn what a dominant is and how it sounds, then sit down at the piano and figure out the chords to some song that's mostly tonic and dominant, and so on. And once you have that down, you can compose some stuff meaningfully.