aphorism - music that defines you

If you could pick a "theme song" what would it be?  The White House residents get "Hail to the Chief", Bob Hope got "Thanks for the Memory", Billy Joel "Piano Man", Sinatra "My Way" ... what would yours be?  What song defines you?  What lyrics hold the most truth for your life today?

The song that resides most comfortably in my daily internal soundtrack is, "Hard Believer" by First Aid Kit.  I'm outing myself here as being non-religious, which is certainly an unpopular thing in the popular media this election season (though increasingly common and open in modern society, strangely).  The melody of the song is simple, the accompaniment sparse (solo guitar and a bit of piano).  The words, though, grab at me almost as well as the amazing "Defying Gravity".