[illusiveman]

Have a look at physiological sight, explained by neuroscientist Andrew Huberman.

Basically, it consists on doing an inhale following by another quick inhale, and then a long exhale.

Theory says that you repeat that pattern 2-3 times, and your stress is drastically reduced for whatever reason I don't remember right now, but he explains it very well in his podcasts and as guest in other podcasts as well.