I want to be happy
But I won't be happy
Till I make you happy too.
Life's really worth living
When you are mirth giving
Why can't I give some to you?
When skies are gray
And you say you are blue
I'll send the sun smiling through
I wanna be happy
But I won't be happy
Till I make you happy too.

(From No No Nanette, 1925 - and here's a band playing it - BS threads are all the better for a bit of music.)