Well, as FumbleFingers suggested, the lyrics to popular songs are not a good way to learn English. For one thing, poets and song writers are given "poetic license" to break the rules of English grammar. For another thing, poets and song writers are also given poetic license to violate logic and common sense. Thus, you can never be sure if you do not understand the syntax or have merely lost your mind.
How the force that drives the green fuse through the flower
Drives my green age
makes no literal sense, but makes emotional sense to anyone who is or was an adolescent.
This song is, in my opinion, completely innocent of any logical coherence and must be interpreted emotionally.
The first line implies that the singer is inside a house watching through a window at life passing by.
The second line implies that the singer is looking from the cold outside into a house filled inside with warmth and love.
So those two lines are literally contradictory but both express adolescent feelings of alienation: I am alone, misunderstood, and missing out.
The final line reverses that: I am NOW OK with who I am and my situation. (As I rembember, this realization strikes a few seconds after you find a lover.)
Now I am not suggesting that this particular pop song has the depth and verbal beauty of Dylan Thomas. But I am suggesting that poetry at all levels of artistry cannot be interpreted literally, particularly poetry in the adolescent mode. (For example, I myself have never been able to make heads or tails of the poetry of Mallarme; I cannot get past the apparent literal meaning of his words. But I would never recommend his poetry as a way to learn French.)
EDIT: I do not mean to disparage poetry in the adolescent mode; only poetry can quite express adolescence.
Si j'avais su ce que je sais
Ce fut tous, mais ce fut assez
is about more than what it literally means; it is as much about how it sounds in French and what feelings the words and sounds elicit.