Though I can see the multilevel analysis from slinky87, this being pop music, I very much believe that this lyric is much more about the desperate nature of living life with fear of never achieving the dreams and ambitions that we so desperately harbor in our youth and the ultimate sacrifices we accept to take, being in pursuing said dreams or in taking on life in it's bluntest, and sometimes dullest, edge.
So basically this is about dreaming and fearing the journey that pursuing that dream entails.