Painter Girl reports there is no easy way to paint a decorative ceiling:

... I will say, on the days that I know I will be doing ceiling work, I also know I will be able to do very little when I get home from work. I am totally beat. I do have a neck brace that I sometimes wear when stenciling on a ceiling. When plastering, I feel I am working at a comfortable angle and moving quickly, so usually don't need the brace, but when stenciling, it's closer, tighter work, and I feel my neck stiffening up almost immediately. ... I know some decorative painters who build in the price of a massage with every ceiling job. ...