Your core includes the muscles of your abdomen and back — it stabilizes you while you sit, stand, walk, and generally move about. A strong, flexible core is the centerpiece of a fit, healthy body, just as a house cleared of clutter is the center of a healthy home.

Today, I want you to focus on strengthening your core. Disciplines like yoga and Pilates target the core muscles, and "core conditioning" classes at your local gym do the same. Definitely try a class if you like, but keep in mind that simple steps, such as paying attention to your posture, have benefits for the core, too.

Proper posture involves a "neutral" spine — that is, you maintain a slight curve in your lower back that gives you flexibility and helps protect your back. Your stomach should be tucked in, your head up. Check your posture several times a day — you don't have to sit and stand ramrod straight, but try not to slump as you tire, which naturally happens to all of us.

Pay attention to your core during your workout today. If you're walking or jogging, make sure you're maintaining good posture. And during strength training, your movements should involve your core. For example, while doing push-ups, focus on keeping your abdominal muscles tight; when you do squats, maintain good posture, with your head up, shoulders back, and tummy tucked in. Even simple exercises like balancing on one leg for a few minutes will strengthen your core muscles.