This workout is one of my favourites, the circle of death is always in my back pocket to pull out to really crush the cardio with my crew. I've done it in the sand on a hillside and even half hill half flat field.
This one is aimed to increase cardio stamina while blasting your clients muscles with different exercises in between. It's always a rocker no matter what fitness level you train this one with. You can increase the intensity by adding in dumbbells or other equipment. If in a smaller space than have your clients do the circle twice before switching with their partner.