Any type of deep breathing is beneficial because it aids circulation and blood flow, especially when stressed. Below is an example of rhythmic breathing that may be helpful:
Inhale deeply, counting to 4; hold for 4 counts.
Exhale, counting to 4; hold for 4 counts.
Repeat entire cycle (16 counts) ten or more times.
Also see earlier post of 7/4 /12 on Wellness – How you breathe.