Standing. It's just something you do, right (like breathing)? The truth is there's a perfectly aligned and balanced way to stand.
Good posture helps relieve and prevent pain, improves your attitude and also positively affects your brain. Even if you don't think you're not guilty of the worst posture mistakes (hunching your shoulder or rounding your back), you might be missing one key part of standing properly: complete balance.
AZ Central notes that starts with the foot, your base of support:
To stand upright, you must balance your body over your feet. Your spine should be aligned over your pelvis, with your weight evenly distributed between your feet. Many people stand with more weight over one foot or with their weight over only part of their feet. While standing, become aware of your feet. You should feel even pressure on the balls of your big toes, little toes and heels. This is the tripod of your foot. If you feel more pressure on one of these points, you are not in alignment. Relax your toes and knees and adjust your weight so the tripods of both feet feel equal pressure.
Putting too much weight on one foot, leaning too forward, and even turning your feet outwards or inwards while standing (they should be pointing forwards) could mess up other parts of your body. Do this for too long (for example, at a standing desk), and it becomes a hard habit to correct.
You can test the other parts of your posture against a wall, but don't neglect the balance over your feet too.
Read more standing posture tips at AZ Central's Healthy Living page.