Both good and bad posture can be influenced by habit. Store these little reminders in the back of your head and try them on a regular basis, they will improve your posture and may help prevent aches and pains.
Standing
Start from the ground up. Stand with your feet underneath your hips and your knees tracking in the same direction as your middle toes. Pretend (some may need to pretend less than others!) that your pants are a size small and draw your belly button towards your backbone (ladies, this should also be a cue to draw up your pelvic floor muscles).
Breathe in deeply and lift your chest slightly, drop your shoulders away from your ears and activate the muscles slightly between your shoulder blades. Check that your chin is not jutting forward and that your jaw muscles are relaxed.
Sitting
Slouching is so very tempting, and so very bad for your back and overall posture. Try and avoid it at all costs. If you are sitting on an office or dining chair, keep both feet on the floor and your lower back towards the back of the chair. As with standing, engage your core muscles by moving your belly button towards your spine and leaving it there. Also repeat the instructions for your chest, shoulders, back and jaw.
Lying
If you suffer from aching hips, it is a good idea to lie with a pillow between your knees to offer support.
Breathing
Your breathing can also encourage good posture. Breathe using your whole lungs, not just the top portion. This reduces stress and makes each breath more efficient. Breathe in through your nose and out through your mouth. Fill your lungs all the way and try to practice slow, rhythmic breaths.