To develop better posture you must fully exhale, activating the diaphragm and restoring proper pelvic position. Do this drill daily to find the best alignment.
1/ Lie on your back, feet flat on the floor. Breathe in through your nose. Notice how your abdominals lift and your tailbone pushes into the floor.
2/ Exhale through your mouth. Push all the air out of your lungs. Your abs will move closer to the floor, your back’s curve will lessen and more of your pelvis will touch the floor.
3/ Hold the bottom of the exhale for 3-5 secs. Your ribcage will come down. Use your lower abs to pull the pelvis into neutral alignment, midback and upper glutes against the floor. On the next inhale, maintain this alignment, breathing into your belly and chest. Take 4-5 breaths this way.