Where to start?
It’s a good way to relax, or get yourself going. If you’ve had a stressfull day, putting on your favorite music can help you escape. I remember one time, when I was feeling really bad and down, I went to the store, and listened to one of my favorite songs by Yes, and by the time I got out of my car, I didn’t feel bad anymore.
Also, it’s a good way to while away the time. If you are working, and you have music playing, the day just seems to go by faster. Which is why most stores, offices, etc have music playing.
And then there’s the dancing factor. It’s hard to dance when there’s no music playing. And dancing is fun.