Box breathing (also called square or 4-on-4 breathing) is one of the most widely used real-time stress management tools. Four equal stages of 4 seconds each: inhale hold exhale hold.
Origins
Popularized by former Navy SEAL Mark Divine as part of special forces training. Used today by Navy SEALs the US Air Force astronauts and elite athletes.
How to practice
Inhale through nose for 4 seconds. Hold for 4 seconds. Exhale fully for 4 seconds. Hold empty for 4 seconds. Repeat 4-8 cycles. Start with 3 seconds if needed.
Science
Regulates the autonomic nervous system. After 4-6 cycles most people report immediate anxiety reduction and improved focus. A 2021 study found daily box breathing practice improved lung function and reduced stress markers. Practice in traffic jams waiting rooms or any short break.