Why focus on breathing ? Breath techniques are so important to general health for more than the obvious reasons. When you hear Yogis discuss breathing for removing of toxins from the body, the link below discusses the science of the make-up of fat cells and how the breath expels these cells. So obviously the body and breath works the same way with other chemicals in other cells in the body.
http://upliftconnect.com/stress-its-not-in-your-head-its-in-your-nervous-system/
Why I teach in my classes the importance of Chanting. The Yogis believed in the effects vibrations have on our body and living things, so they use chanting to cleanse the mind. Additionally cleansing the energy field in our natural state of creation, that is a by-product of everything inside the human body that creates and absorbs energy.
The links below explore the Biofield, Epigenetics and how we are effected by energy of our surroundings, frequency & vibration.
https://phys.org/news/2016-10-scientists-effects-infrasonic-vibrations-humans.html
http://www.biofieldscience.org
https://www.britannica.com/science/infrasonics
http://blog.sivanaspirit.com/sp-gn-scientific-benefits-chanting/
http://www.potentialsandpossibilities.com/the-science-of-mantra-chanting/
http://www.ncbi.nim.nih.gov/pmc/articles/PMC3099099/
https://www.scientificamerican.com/article/could-certain-frequencies/
https://www.ncbi.nlm.nih.gov/pubmed/9306739
Check out the documentary 
Check out this documentary 
Sometimes things happen in life that push us over the edge.