Box breathing technique

box breathing or four-square breathing.

Here's how it works:

1. Breathe in for four seconds.
2. Hold air in your lungs for four seconds.
3. Exhale for four seconds.
4. Hold your breath, lungs emptied, for four seconds.

from : https://getpocket.com/explore/item/beat-stress-like-a-navy-seal-with-this-ridiculously-easy-exercise