I had a hard time with this and narrowed it down to 3 songs. Unwritten, Pocketful of Sunshine and Soak up the Sun.
Unwritten will be my official theme song because it is such a positive song about how you have your whole life in front of you and that you can choose to make of it whatever you want. The other two support that concept- Pocketful Of Sunshine referring to how you won't let the dark things of the world get you down and Soak up the Sun further reinforces that thought but illustrating how no matter how much or how little you have you can still be positive and see the brighter things in life.
I hadn't seen the videos for any of these songs before today; so I was a little nervous that I might hate the songs after I saw them (you never know what you'll get from a music video!) THANKFULLY I quite enjoyed the videos and they supported the messages of the songs (for the most part)