Emergency exit

I'm water under the bridge you cross
With streams pulling me towards the sea
I'm a ready-made float on a desert island
That will get you to where you want to be
I'm a crossword you'll find all the letters for
'Cause yours is the only language I speak

Even if you've got nothing to escape from
I'll be your emergency exit
Just look for my sign
In bright neon it says:
Stay here, be mine

I'm your favourite song put on repeat
Over and over again the soundtrack of your life
I'm a pacemaker to keep your heart beating
My monitor shows what happens in there
I'm the mirror mirror on your wall
Saying you're the most beautiful of them all

Even if you've got nothing to escape from
I'll be your emergency exit
Just look for my sign
In bright neon it says:
Stay here, be mine