This structured ab workout targets different regions of your core using only body weight, making it perfect for both beginners and intermediates. The workout comprises four key exercises, each focused on strengthening and toning your abdominal muscles.

1. **Floor Crunches**: Begin by lying flat on your back with your knees bent and feet flat on the floor. Perform three sets of ten repetitions. While doing crunches, ensure you lift your upper body off the floor using your core strength, keeping your neck and head relaxed to prevent strain.

2. **Alternate Oblique Crunches**: This exercise targets the oblique muscles, which are crucial for rotational strength. Start the same as a regular crunch then alternate twisting your torso to touch your elbow to the opposite knee. Complete three sets of ten reps for each side. Keep your movements controlled and steady to maximize engagement of the obliques.

3. **90 Degree Heel Touch**: Although minimal equipment might be used for enhanced effect, the basic version requires only your body weight. Position yourself with your legs lifted and bent at 90 degrees. Reach alternatively towards your heels, touching them, if possible. This move aggressively targets the side abs. Perform three sets of ten touches per side.

4. **Alternate Leg Raises**: Finish your routine with this challenging lower ab workout. Lie flat, lift one leg at a time to the ceiling while keeping the other leg slightly elevated off the floor. This not only improves lower abdominal strength but also enhances stability and control. Execute three sets of ten reps per leg, maintaining a slow and controlled lift to avoid any lower back pressure.