Box breathing can be thought of as the opposite of a panic attack. It can also be performed discreetly. What you need to do is sit upright, with your feet flat on the floor. After slowly exhaling, you slowly inhale through your nose to the count of four. Your lungs fill with air while you hold your breath for another slow count of four. Then you exhale through your mouth for four more beats, and finally, hold your breath one more time for four counts before repeating the process.