I have noticed that I have a subliminal soundtrack in my mind most of the time, and the songs on it coincide nicely with life themes. Most of the songs on my playlist are hymns and oldies. Because of the theme of Joy I have been pondering lately, "Rejoice in the Lord Always" has been on repeat, taking turns with "Oh Praise Him," "The Joy of the Lord is my Strength," etc.
I personally believe that God created music as a memorization tool to learn scripture, and a meditation tool to help us contemplate His Glory. Of course, we can use it to memorize or meditate on everything else as well, and people do. This is why people learn lyrics without even trying when music is in the background. Advertisers are obviously aware of this!
I wish my playlist was always as good as it is today. When things get really stressful, I'll find, "I Want to Break Free" by Queen, "Monday, Monday" by the Beatles, "Hotel California," or any number of Eagle's Songs get stuck in there. Sometimes I get junk in my head I can't get rid of (like Lady Gaga, or Madonna, ew!!!) or life gets so overwhelming I can hardly hear the soundtrack at all.
What about you? What soundtrack plays in your head? What's on your playlist?