Original caption
Most people think pulling your shoulders back fixes their posture. That's not what's happening. Pulling your shoulders back just fights the compensation without touching the cause. Your posture is a chain. Your feet collapse, your knees cave to compensate, your pelvis tilts to compensate for that, and your lower back rounds forward, pulling your shoulders and neck along with it. Compensate long enough, and it turns into chronic back pain, tight hips, and rounded shoulders that get blamed on sitting too much instead of the pattern that caused it. The fix isn't standing up straighter. It's finding the weakest link…not the one you can see.