There is lots of information online about Coherent Breathing:
Basically, I took some ideas for the heart-focussed breathing from HeartMath (called the Heart Lock-In technique which is breathing into and out of the heart while feeling a very pleasant emotion) and added it to the information I found in books and online about a scientifically proven breathwork style called Coherent Breathing so you don’t need to purchase the electronic breath coherence monitors (HeartMath sells a few of these)
HeartMath also has done MUCH research on the heart-brain connection and I recommend you check out their site and look around.
This is a really great video about the HeartMath Quick Coherence technique. It does not mention the 5 or 6 second breath cycle and does mention all the other steps. And, another video that highlights the HeartMath technique while digging more deeply into the emotional component.
Realize that some “experts” recommend that you breath this way while sitting up while others say you can lay down while practicing. It seems that sitting up is more natural to my way of thinking. You can try it both ways and see if one is better for you.
The only thing to add to the instructions in that previous article and other online information is to imagine that you are breathing in and out through your heart and feeling a positive emotion such as gratitude or love while you are imagining breathing in and out through your heart. This step is the core of the HeartMath technique.
A very good video that teaches Coherent Breathing but without the HeartMath ” addition of heart breathing.
And here are some free breath pacers that you can use to support your Coherent Breath practice
And there are a number of great books on the subject of Coherent Breathing:
You will probably enjoy viewing this great video by Gregg Braden on Heart-Brain Coherence.