Wait, can this be true? Have we really gotten this far into the thread and NO ONE has suggested "Defying Gravity"??
All kidding aside, it's definitely a song about being true to yourself, pushing boundaries, and seeing how far you can go.
Also, "Astonishing" from LITTLE WOMEN.
"Word of advice: Be who you are, wear what you want---just learn how to run real fast." Marc, UGLY BETTY