This is a great song. Though, what Josh Groban song isn't a great song. I don't have much to say about it structurally or harmonically, because the emotional content of this song takes over completely after the first phrase.
It begins with piano introduction, simple thirds playing the melody. Josh repeats the melody and then goes on to do so a bunch of times. One of my favorite parts is the direct modulation about 3/4 of the way through the piece, you're expecting the same old melody just more powerful with the orchestra behind it at a louder dynamic, but instead you get the direct modulation and thats a great moment.
I heard this song for the first time at my sisters dance competition, its the song she uses for her solo that she competes with. Its really interesting because there is a chord on the word "fly" and then "alive" (see lyrics at the end) that actually sounds tonally open and ethereal like flying, and on that word she does this really hard, continuous pirouette, is almost programmatic.... I liked it.