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Sit Up and Smile
You've heard that good posture can make you appear taller, thinner and more confident, and now research shows that it can make you feel happier. And "enthusiastic," "excited" and "strong," as well. Those are some of the words that straight-backed people used to describe their feelings in a New Zealand study of the effect of posture on mood. Other measurements, such as blood pressure and heart rates, showed that the people who were forced to sit up straight were more alert, and good posture was associated with higher self-esteem and less social fear. As for those who were instructed to slump: They reported feeling "fearful," "hostile," "nervous," "passive" and "sluggish." Previous research has shown that upright posture causes increased temperature and heart rate, as well as elevated epinephrine and norepinephrine. Sitting up seems to immediately give people a jolt.

Microchange: Set a timer to remind yourself to get up every 20 minutes. It's easier to completely reset your posture than to adjust it in your seat, says Steven Conway, a Wisconsin-based chiropractor and spokesperson for the American Chiropractic Association. Stand up, arch your back, twist from side to side and roll your shoulders back. When you sit down, scoot your bottom against the back of your chair, and focus more on pulling your shoulders back than keeping your back straight (putting a ball behind you can help).