I'm different from most people on this one. I've bought a LOT of musical instruments over the years, hoping in each case that talent would jump out and bite me. For each one, I wanted to play music that I liked, where that instrument starred in those pieces of music.  I would work at it for a while (sometimes quite a while) and finally get discouraged and not bother anymore.

For violin, I didn't have any particular piece (or even genre) that I wanted to play. I also knew almost nothing about the instrument.  I decide very rapidly I needed lessons. (The world has been uncooperative about that - my teacher had no slots for 4 or 5 weeks, then I managed to get 3 lessons, then he went on vacation for 3 weeks. I'm thoroughly sick of the first 2/3s of "Boil them cabbage down" by now. )

My end goal is to be able to sight-read a piece of music, and play it decently at or close to normal tempo.

I've found a number of tunes that seem easy and I know what they're supposed to sound like ("Ode to Joy" was one I've picked up, although I have yet to see the music.)  I don't have any major pieces of music that I'm striving for yet, though. I'm still trying to acquire the basic skills.