Just picture a cup with water. When you fill it, the bottom fills first, the top last. When you empty it, the top will be gone first and the bottom last. And that's exactly how your lungs work as well. Stress often shows in bad posture and muscular tension in shoulders, neck and back.
Breathing difficulties can reflect deep shock.
Your stomach may be sensitive to your emotional state. Focus on what you can sense. Research reveals that the meditative practice generally known as mindfulness can have a tremendous calming effect. You may be surprised by how much more relaxed and alert you become. The list is endless.