If you're not a professional ballet dancer, chances are good that your posture could use a little tune-up. It's surprising how much better you can feel when you stand up straight - taller, even lighter, too!
Assess your stance by having a friend photograph you - front, back, side - standing naturally. Are your shoulders and hips aligned? Are your head and neck directly above your shoulders? From the side, is your ear is aligned with your shoulder?
To help correct slouch when you sit for long periods, take a few minutes every hour to get up and stretch your back, neck, and shoulders to relax those muscles. It will help keep your body from falling into bad habits!