Sometimes you're just given a picture.
While working in a fabrication plant, I saw this gentleman whose job it was to take a red-hot hoop of metal from one machine to another using tongs. Each time he passed the hot steel across it framed his face for a split second. All I had to do was make my shot at the right moment to circle the workers face in the Ring of Fire. It was all timing. The glowing metal provided a ring light to illuminate his face. And yes, it was hours before I could get that Johnny Cash song out of my head.