Q: Am I ever going to get a flat stomach? EXERCISE: Tuck-in Plank: 1. Come onto all fours and move into the top of a push-up position: arms straight, hands directly beneath your shoulders with fingers spread on the mat, feet straight out behind you, balancing on your toes with your hips low, and back fl at. Make sure your weight is evenly distributed between your hands and feet. 2. Using your abdominal muscles, pull your right knee toward your chest, bringing it in as close as possible. Repeat with the left knee. Alternate right and left 12 times.