How to keep calm under pressure with 1 breathing exercise. BOX breathing is a great way to keep calm in stressful conditions and it’s even been used by the military to stay calm and focused whilst in hostile situations. Breath in for 4 seconds, hold for 4 seconds, breath out for 4 seconds and hold again for 4 seconds. Visualise with each stage you are drawing the side of a square box. This will help tap into your rest and digest nervous system and allow you to make more rational decisions under pressure!