Found this easily enough

The post is at
http://forum.quoteland.com/eve/forums?q=Y&a=tpc&s=586192041&f=785191641&m=8361979722
I contacted Mr. Purkey asking him (here is the beginning of my message to him):
Are you the author of a quote that goes something like:
"Dance like no one is watching,
Work like you don't need the money..."

and this is his reply:

Dear John,

Thanks for your note regarding the quote. It is
obvious that the theme has worked its way through many minds.
I certainly want to give credit to those who have tinkered with this beautiful concept.
My version follows. I am sure that most of the words are mine.
"You've gotta' dance like there's nobody watching,
Love like you'll never be hurt.
Sing like there's nobody listening,
And live like it's heaven on earth."
(And speak from the heart to be heard.)
Hope this helps.
Best wishes,

William W. Purkey