Music is pretty well the biggest motivation for me as a writer. I know lots of writers feel the same, with music of all genres playing large parts in our creative process.
I remember very vividly connecting with a song back in high school. I think it was "Into the West" by Annie Lennox on the Lord of the Rings: Return of the King soundtrack. I adored that song. Still do. Anyway, I had discovered that I could just put a song on repeat and let it go for hours without getting sick of it. I'm still that way. There are songs I could probably have run on repeat for a whole day and I'd be happy to have it.
My brother, not so much. I remember him walking by my room after what very likely was an hour of "Into the West" playing and begrudgingly reminding me that there was more music in the world than one song. To this day, if I put a song on more than once, he'll give me this look that kinda says, "Really? We're gonna listen to this one again?"
I just spent very likely two hours listening to the same song on repeat as I tried to work through a scene in book 3. Why that one song? Well, mostly 'cause I have yet to find another song that will evoke the same level of feeling as that song does for this one particular chapter in the book. I love the song on its own merit, don't get me wrong, but beyond this chapter I don't necessarily need it in my soundtrack to book 3 playlist. (It's "The Burning Bush" by Hans Zimmer from the Prince of Egypt soundtrack by the way).
There are songs I have on my iPod specifically to connect me with one character, or with one scene, or in some cases a whole book. Where I'll see whole flashes of scenes fly across my mind. For instance, "Gates of Pearl" by Really Slow Motion just popped on and my brain has legitimately jumped straight to a specific character's story and is starting to fly through scene after scene from his life and how he became the person he is in the story.
Ask the writers in your life what music connects with them. Music pulls at our minds and our hearts so quickly and so effortlessly that we can in an instant be thrown right into the thick of our world at the first few seconds of a song. It's an amazing thing about music, that it can legitimately transport us to other stratospheres over the course of a few short minutes. And those minutes never seem long enough for my favorite songs. Hence why I tend to put things on repeat.
This is also why I wear headphones while writing.