We've been told to stand up straight as long as we've been able to stand, but sometimes it's harder than it seems.
We know why we should do it: Good posture looks good, feels good and makes us look slimmer. On the flip side, studies have linked poor posture with lower self-esteem, depression and back pain.
But sometimes posture pointers are confusing.
Remember when we were all supposed to use Pilates balls instead of office chairs? Well, claims that doing so improved posture were recently disputed by researchers at the University of Waterloo in Ontario. They found that it didn't help - or hurt - posture.
But there are still some things you can do to help your stance, as well as some things you can avoid to keep it from getting worse.
HELPSReposition your monitor
Your monitor should be 1 to 2 feet away from your face, and your eyes should be level with the top of the monitor, says Janice Novak, author of "Posture, Get It Straight! Look Ten Years Younger, Ten Pounds Thinner and Feel Better Than Ever." This will prevent your head from leaning forward and away from your shoulders.
Place a lumbar roll behind the small of your back when you're sitting in a chair, according to Richard Guyer, orthopedic surgeon and co-founder of the Texas Back Institute.
"It helps to maintain the normal curvature in the back when sitting," he says. "There is a tendency for the lower curve to flatten, which can cause fatiguing with prolonged sitting."
Reposition yourself in your car while driving
Move your seat close enough to the pedals so that your knees are bent. A 90-degree angle would be too bent, and anything more than 130 degrees would be too straight. (Make sure your body is at least 13 inches away from the steering wheel in case your air bag deploys.) Your lower back should be against the back of the seat. Sit in an upright or slightly reclining position. Adjust the headrest so your head is actually resting against it. This position places your head directly over your spine and allows your neck and upper back muscles to relax while you drive, Novak says. Finally, when holding the steering wheel, your elbows should be bent at 120 degrees.
Strengthen your core muscles through exercise
Do three sets of basic and side planks daily, holding each pose for 30 seconds, says Levi Harrison, a Los Angeles orthopedic surgeon and author of "The Art of Fitness: A Journey to Self Enhancement." Start in a pushup position with your arms directly under your shoulders (you may bend your arms if necessary) for the center plank. Keep your head aligned with your neck. After 30 seconds, turn to one side by lifting your left arm and stacking your body over your right leg, keeping your right arm extended on the ground. You may bend your right arm if necessary. Then switch sides.
Heels higher than 1 inch increase your sway backward, which can lead to lower back discomfort, Novak says. Your foot slides to the front of the shoe, which puts too much pressure on the ball of the foot and your toes. High heels also shorten the muscles and tendons on the back of your ankle, and stretch and weaken the muscles on the front of your ankle, which can lead to shin splints. Heels on shoes also get in the way of the natural stride, which is to place your heel down first, then roll through the ball of your foot. If you must wear heels, don't wear them for longer than four hours at a time.
When you're resting your legs in a straight extension, you're placing stress on your lower back, says Mary Ann Wilmarth, chief of physical therapy at Harvard University. Sitting this way can stress your sciatic nerve and may put you in a slouched position without supporting your back. A better alternative would be to rest with both knees bent.
You should not be able to sink into a couch, Wilmarth says. "It needs to be firm enough to give you support." If your couch doesn't support your lower back, you can use extra pillows to assist it.
Notice where your head is at this very moment.
"Is it completely focused on the page or the screen? What's going on with your shoulders right now? Any tension there? Is your chin jutting forward?" says Lindsay Newitter, spokeswoman for the Alexander Technique and certified in teaching the Alexander Technique, an educational method studied by musicians, actors and athletes aimed at improving posture that's been in practice for more than 100 years.
"There's a learning process involved in unlearning habits, but a great first step is to start developing an awareness of yourself in the midst of activity," she says.