Your Emotional Playlist
If you've taken an exercise class at your gym, the instructor most likely played upbeat, high energy music, not only because the tempo and rhythm suited the exercise combinations but also because the music was energizing. He or she selected music that would inspire you to exert yourself. A yoga instructor might use New Age music instead, to put you in a peaceful, contemplative state of mind conducive to stretching.
I'm not the first to note that music is pure emotion. It may give voice to emotions we're already experiencing, but it can also induce new feelings within us. No doubt you have favorite songs that reliably stir up certain feelings whenever you hear them.  Many people turn to music for emotional congruence: if they're feeling blue because a relationship ended, they may listen to torch songs; if they're happy, they may want to hear something joyful. But we can also use music in the exact opposite way -- listen to something upbeat in order to cheer ourselves when we're down.
We can use books and movies in these same ways, especially when it comes to old favorites. No matter how many times I've seen it, I watch It's a Wonderful Life almost every year at Christmas, and I still get weepy when the people of Bedford Falls file through George and Mary's front door with cash to save him from the bank examiner. I like to feel moved and I watch the film in part because I look forward to that experience. I've read The Portrait of a Lady eight or nine times and I'm always devastated by the end. Part of my goal in rereading the novel is to revisit that pain.