Sunset Boulevard (1950)
A:       Norma Desmond (Gloria Swanson) 

A:       I can't go on with the scene.  I'm too happy.  Mr. DeMille, do you mind if I say a few words?  Thank you.  I just want to tell you all how happy I am to be back in the studio, making a picture again.  You don't know how much I've missed all of you.  And I promise you I'll never desert you again.  Because after Salome, we'll make another picture and another picture.  You see, this is my life.  It always will be.  There's nothing else.  Just us... and the cameras... and those wonderful people out there in the dark.  All right, Mr. DeMille, I'm ready for my close-up.

This line is #7 in AFI's 100 Years... 100 Movie Quotes.