"Isn't it ridiculous?" says Charlie, rolling his eyes. "Most of the grown-ups i know don't know what they want to do forever, either. They just know what they've ended up doing right now."
Other options:
no subject
"Isn't it ridiculous?" says Charlie, rolling his eyes. "Most of the grown-ups i know don't know what they want to do forever, either. They just know what they've ended up doing right now."