Simply get into a good postural position (standing nice and tall with shoulders back and down and head back). Now note the distance between the bottom of your sternum and your pubic bone/pelvis. In most people this will be around about the distance between the tip of your thumb and little finger when doing the Shaka or ‘hang loose’ sign.
So the hack is simple. Just do your Shaka sign, place your thumb at the bottom of your sternum and then lift your chest upwards so the little finger is close to your pubic bone. Simply getting this distance right will naturally stand you up tall, your shoulders will go back and down and your head should move backwards. Straight away you are in a better postural position.
Whenever you think about your posture, no matter whether you are sitting, standing or bending over, simply using this hack will improve your posture. The more you can do it, the more natural it will be and the better your posture will become. Your body will thank you for it.