"A New Start" is a song from The Amazing World of Gumball. It is sung by Gumball and Darwin in the episode "The Kids" while their voices are broken and deep, just before the two main characters get their new voices.
Gumball: Maybe it's for the better
No-one wants to stay a child forever
Darwin: Remember the wonderful times we've had
Those happy thoughts now make me sad
Both: They say it's not bad
It's just a new start
So why do I have
This pain in my heart?
Our childhood memories are getting hazy
But soon we can drive, go to college, and we both go crazy!