One of the easiest ways to strengthen your abdominal muscles -- and support your back -- is through good posture.

You may feel like you're already standing straight, but in reality, most of us stand like the Leaning Tower of Pisa. Practice good posture by bringing your head and neck back. The key element is breathing in to tighten your gut. That's the component that lifts your chest and will give you Marine-like posture.

Sometimes the smallest changes in your life can lead to the biggest results. Sucking in your gut while you do crunches, or even when you take the elevator, is a good example. It helps your body not only look younger -- by skimming a couple of inches off your middle and adding them to your lungs/chest -- but it also helps your body get stronger, because you're engaging your abdominal muscles.

Here are the five steps to perfect posture:

1. Pull your shoulder blades back slightly toward each other and down away from your ears.
2. Lift your chest up and out.
3. Pull your head back just enough to keep it in line with your spine.
4. Position your pelvis or hips to create or maintain a natural arch in your lower back.
5. Pull your belly button in toward your spine without changing or tilting your hips or losing the arch in your lower back.

Is your back barking? Take this symptom checker for advice.

The RealAge Workout. Roizen, M. F., Hafen, T., Armour, L. A., New York: Harper Collins, 2006.