Just 10 minutes a day will improve stress, focus and aid workout recovery.

Try this 6 Second Exercise and also the 5.5 Second Exercise to see which you find more relaxing. I find the 6 second better for my body, but it just depends on the nervous system. 

Hit me with questions or comments. 

From the National Library of Medicine: 

"Heart rate variability biofeedback (HRVBFB) or resonance breathing is breathing at a slow rate, usually 4.5 to 7 breaths per minute, which depends on each individual, to maximise their RSA. Self-training in resonance breathing lowers stress, blood pressure, and improves mood. Training on resonance breathing improves vagal tone, thereby improving HRV, which is an index of stress and health."