Deep breathing has numerous health benefits: it decreases your stress response, blood pressure, and heart rate, making you calmer. Shallow breathing is associated with tension and anxiety. Many people don’t breathe deeply due to societal pressures to have a flat stomach. Breathing deeply will push your lower stomach out.
Since deep breathing is unnatural for many, you must make a conscious decision to breathe differently to practice it. It might feel odd at first, but you might start breathing deeper naturally with practice over time. Some breathing exercises are also targeted explicitly towards decreasing anxiety: alternate-nostril breathing, belly breathing, box breathing, 4-7-8 breathing, lion’s breath, etc.
Next time you notice your breathing becoming shallow, try making a conscious effort to take a deep, belly breath.