Developing core strength is essential for fitness and overall health, but it doesn't have to be a drudge. If you're ready to go beyond crunches — or never liked them to begin with! — consider these moves that target the muscles in your torso and spine.

The Advanced Bird Dog: Begin on your hands and knees. Contract your core muscles and straighten your right leg behind you until it's level with your hip. Now raise your left arm straight out in front of you to shoulder level. From this start position, draw in your right knee and left elbow, touch the elbow to the knee if you can, and then straighten them back to the start position without touching the floor. Do one set, then switch sides and repeat.

The Plank With Knee Drive: Begin on your hands and knees. Straighten your legs behind you, shifting your weight to the balls of your feet. Contract your core muscles and, with control, bring one knee toward your chest and then back out to the starting position. Alternate legs throughout the set.

The Lying Single Leg Extension: Lie flat on a mat and then draw in your knees so that they make a 90-degree angle with your thighs; calves are parallel with the floor. Contract your core muscles. Keep your back pressed into the mat as you press your right foot forward to straighten your right leg -- the left knee never moves. Then bring the right leg back to the start position and repeat with the left leg. Alternate legs throughout the set, always keeping the back pressed into the floor.

For each exercise, start with two sets of eight reps each. As you get stronger, build up to 12 reps per set, and then increase to three sets, starting with eight reps and building to 12.