Seated Russian Twist You can do this quick ab exercise in your living room. Sit on the ground with your knees bent, pull your abs to your spine, and lean back a few inches while keeping your back straight. Hold your hand at your chest, and twist your torso to the right, then to the left to complete one rep. Continue twisting from side to side for 15 reps. Image Source: POPSUGAR Photography / Kathryna Hancock