Close your eyes for a moment (or don't, since you won't be able to read this).
Imagine releasing the weight from your body, one part at a time.
Begin at your feet, and work your way up until you've lost all weight and tension.
There is no longer anything left to chain you down.
Feel yourself being lifted out of your body, higher and higher.
Then, open your eyes, letting yourself be taken in by the vibrant colors.
Brilliant crimson pours in from the horizon, with only a fleeting glimpse of the sun to be seen.
Orange trails into a dusky purple, and glistening stars begin to ignite the sky.
Infinite potential stretches below you.
Embrace the warm breeze guiding you forward.
And move wherever your heart takes you.
I feel like a total dork for posting something like this, but this is honestly the feeling I get from the song. As a bit of story time, a couple years ago I took biofeedback lessons, which pretty much means learning to control your heart rate and relax your body. The main technique is just controlled breathing but you can also use imagery and stuff. I doubt my attempt at writing it down did it any justice, really, but hopefully you can roughly get the sense I did. I turned the lights off and closed my eyes while listening, as well as paying complete attention to the song, which is why I ended up visualizing. Normally I don't go out of my way to immerse myself in the music, so this is a special case.
If you want a more verbal description, I think @Pepe pretty much nailed my thoughts. Very light. Personally, it strikes me as uplifting and hopeful rather than sorrowful, but I think the song could be a glass half-full or glass half-empty type deal.
So, uh, I hope that helps you out. Stay tuned for more crap that @LinkThinks.