How do you know when a painting is finished?

When I get within a day of finishing a painting, I am always filled with trepidation. For as long as I am working on a painting, I know that I can change, improve,and remove things and I don't have to take any responsibility for the finished article becasue ........... it's not finished. But every painting has to be finished at some point and declaring a work 'finished' takes some courage. So, I take it slowly on that last day (or two). I sit and look at it a lot and decide upon some small finishing touches...... then I do it. Here is a video to show how it is for me...