A steady, controlled breathing rhythm over a sustained period can have a calming, centring, and energizing effect for the breather.
This style of breathing exercise has been practised for centuries by shamans, meditators and layperson alike.
Breathe in through the nose for a slow count of 8.
Hold for 4 counts.
Breathe out through the nose for a slow count of 8.
Pause for 4 counts.
Continue for several minutes.