When it comes to whole body exercises (e.g., moves that not only work multiple muscle groups but also multiple areas of fitness - strength, endurance, cardio, etc.), squat thrusts are up there when it comes to effectiveness and intensity. Squat thrusts, which are a form of burpees, involve jumping the feet in an out from a plank position. That doesn't sound like such a big deal until you try it...or your trainer makes you try it, at which point you may suggest that said trainer should add the exercise to your ongoing list of "Exercises I Hate."
When you do, you'll find it's an excellent move for the core, the lower body and the heart rate (although you may not feel the cardio part until the exercise is over) and the addition of the Gliding Discs adds even more depth to the core portion of the exercise. Not only will your abs and back work harder, you'll really feel this in your quads each time you pull the knees in. I really love this exercise for building overall core strength and endurance.
Do it right: Squat to the floor with the balls of the feet on the Gliding Discs (you can also use paper plates or towels, if you have hardwood floors). Push the legs out straight, into a plank position, and quickly pull the knees back into the chest, moving the knees out and in as quickly as you can. Keep the core braced throughout the exercise. Repeat for 30-60 seconds.