I found this move in my latest copy of Oxygen magazine and remembered how much I love it while doing it today. It's a great multi-muscle toning move, which strengthens your back, core, arms and legs.
Stand with your feet hip-width apart, holding a single dumbbell with both hands, your arms extended out in front. Then, step your right leg forward, bending both knees to drop into a lunge. Rotate your torso to the right and then to the left, moving as far as possible through your entire range of motion. Return to the start. Repeat the move for 3 sets of 12 repetitions. Make sure to alternate your lunging leg.
To take it up a notch, hold a dumbell or medicine ball while doing the move.