Reverse Crunch This exercise will work your lower abs. To start, lie on your back on a mat with your knees bent, feet flat on the floor. Place your hands behind your head. Engage your core as you raise your knees towards your chest. Lower towards the floor, but stop right before your feet touch. Perform 3 sets of 10 reps with 45 seconds of rest in between. Bicycle Crunch This exercise will work your upper and lower abs. To begin, lie flat on your back on a mat and place your hands behind your head. Engaging your core, lift your head off the ground aiming your right elbow towards your left knee. At the same time, lift your left knee towards your right elbow. Then, switch sides, bringing your left elbow towards your right knee. Complete 3 sets of 10 reps, resting for 45 seconds in between. V-Sit Crunch This exercise works many abdominal muscles, including the inner and outer obliques. To begin, lie flat on your back on a mat with your arms fully extended behind you. Keep your feet straight out in front of you. Engage your core, lifting your right leg towards your left arm as you lift your left arm towards your right leg, raising your head and shoulders. Touch your hand to your shin. Return to the starting position and repeat on the opposite side. Standing Crunch This exercise targets your lower abs. Start by standing tall with your feet hip-width apart. Extend your arms fully towards the ceiling with your palms facing each other. Engage your core to lift your right knee to hip height. At the same time, lower your arms to your sides. Return to starting position and repeat on the opposite side. Do 3 sets of 8 reps with 30 seconds of rest in between. Kickboxing Crunch This exercise works your entire core, especially the lower abs. Stand tall with your feet hip-distance apart. Keep your left arm bent high with your hand near your face. As you engage your abs, do a squat and jab with your right arm. Then, pull your right knee towards your chest to do a crunch. Next, kick out your right leg in front of you with your hands at your sides. Repeat 8 times before switching to the other side. Perform 3 sets on each side with 45 seconds of rest in between.