Oh I should also mention that its good too when you are done or at times throughout to close your eyes and tilt your head back and sometimes the image will appear. This can sometimes get you to go even deeper. Sometimes I will just see a black box when I close my eyes but if I look into it long enough the image or some other image will appear and draw me into it.

I find these kinds of object focused exercises especially helpful when my mind is racing. Having something to focus on besides breath can make it easier to not be distracted by random disruptive thoughts.