As a dyed in the kleenex sentimentalist* I love all of this song (apart from the key change bit towards the end, unfortunately).
But I draw your attention to the use of the word "impossible" in the chorus (which starts almost immediately, the following line being 18 seconds in) -
"Am I the only who thinks it's an impossible task?"
This could be totally accidental but the word "impossible" doesn't fit smoothly into the rhythm/cadence of the singing here but the way she fits it in, dragging it out "im-poss-ible" seems to me both audacious and perfectly, improbably fitting.
*woops make a wanking joke