Just before starting to close your arms you should lean a little backward by pulling your shoulder blades back. (ashotofadrenaline.net)
I think I then got a shoulder strap to pull my shoulders back while I walk to maintain better posture. (perfecthealthdiet.com)
In a standing position, tuck your chin and pull your shoulders down and back by thinking about sticking your shoulder blades in your back pockets. (darwinian-medicine.com)