Posture is the way you hold your body while standing, sitting, or performing tasks like lifting, bending, pulling, or reaching. If your posture is good, the bones of the spine — the vertebrae — are correctly aligned.

Four steps toward good posture

You can improve your posture — and head off back pain — by practicing some imagery and a few easy exercises.

• Imagery. Think of a straight line passing through your body from ceiling to floor (your ears, shoulders, hips, knees, and ankles should be even and line up vertically). Now imagine that a strong cord attached to your breastbone is pulling your chest and rib cage upward, making you taller. Try to hold your pelvis level — don't allow the lower back to sway. Think of stretching your head toward the ceiling, increasing the space between your rib cage and pelvis. Picture yourself as a ballerina or ice skater rather than a soldier at attention.
• Shoulder blade squeeze. Sit up straight in a chair with your hands resting on your thighs. Keep your shoulders down and your chin level. Slowly draw your shoulders back and squeeze your shoulder blades together. Hold for a count of five; relax. Repeat three or four times.
• Upper-body stretch. Stand facing a corner with your arms raised, hands flat against the walls, elbows at shoulder height. Place one foot ahead of the other. Bending your forward knee, exhale as you lean your body toward the corner. Keep your back straight and your chest and head up. You should feel a nice stretch across your chest. Hold this position for 20-30 seconds. Relax.
• Arm-across-chest stretch. Raise your right arm to shoulder level in front of you and bend the arm at the elbow, keeping the forearm parallel to the floor. Grasp the right elbow with your left hand and gently pull it across your chest so that you feel a stretch in the upper arm and shoulder on the right side. Hold for 20 seconds; relax both arms. Repeat to the other side. Repeat three times on each side.
• Practice these imagery and posture exercises throughout the day. You might try to find a good trigger to help you remember, such as doing one or more of them when you get up from your desk, or right before scheduled breaks and lunch. Soon it will become a habit.

Source: Harvard Medical School Healthbeat