The Specials, Enjoy Yourself (It's Later Than You Think)
All over the internet it's:
It's good to be wise when you're young
'Cos you can only be young but the once
Enjoy yourself and have lots of fun
So glad and live life longer than you've ever done
It's not "So glad and live life longer than you've ever done" though is it?
I've always heard it as "So go out and live life [something, better?, forever?] than you've ever done" but I think that's wrong as well.
Totally irrelevant, unless you happen to be in your early fifties and thinking 'WTF?' about life. 