This song is so gorgeous~
I think the meaning is obvious, that you only live life once, and the singer wants to live it to the fullest. She knows the best is to come, and is planning a better life.
I played this cd while I helped my cousin pack for college (we're both major Disney/Pixar freaks). She was so happy to be headed where she was, and I thought it fit the feeling. We were both bawling like little kids by the time this song was done; you;.