"Simple breathing techniques" refers to easy and uncomplicated methods of controlling and focusing on your breath to improve relaxation and overall well-being. Full definition
In my first labor, I was amazed at how well I coped with simple breathing techniques, and then proceeded to panic and lose all faith in my body's ability. (breastfeedingtoday-llli.org)
For example, I teach most patients simple breathing techniques that come from yoga, which I have found to be strikingly effective for an incredible range of conditions, from heart arrhythmia and high blood pressure to chronic digestive problems, such as irritable bowel syndrome and reflux disease. (discovermagazine.com)
It was fun to see how simple breathing techniques, movements, touching, and just turning my attention to my erogenous zones could make me want to have sex. (health.com)