Box Breathing
It's been known for thousands of years in yoga as "samavritti pranayama", or "square breath". The advice is to count on the finger of one hand. Inhale while stepping 1 2 3 4, Hold 1 2 3 4, Exhale 1 2 3 4 and Hold 1 2 3 4. All of this without mentally counting, just use your fingers to do the steps. It is recommended before meditation for calming the agitated mind.Another method is to count breaths in increasing cycles: 1; 1 2; 1 2 3; ...; 1 2 3 4 5 6 7;... Each number corresponds to one inhalation and exhalation. See how high you can count before making a mistake. This comes from Buddhism.