Becoming Unfamiliar with Ourselves

Last year during yoga, I noticed something interesting and slightly concerning. When instructor instructed us through breathing techniques, he explained the incidence of lung expansion and general physiological expansion when we inhale, and opposite as we exhale. He asked us to notice as our belly was moving outward, and space created as our ribs expanded. I noticed mine did not. It was infact the opposite. As I inhaled, my belly went in, and apparently contracted, while exhaling made my belly flow outward. This was not intentional. Hmm.  
​​
Today someone pointed out I may be a reverse breather (its a real thing?!). And I possibly acquired this without realizing due to past frequent anxiety issues. When we get information that may not be easiest to process we often go 'HA!'  where we sharply inhale (open jaws) and tuck our belly in. Interestingly, in Taoist tradition, it is a technique used to build stronger immune system, increased lung capacity and increased energy (https://www.livestrong.com/article/155298-the-effects-of-reverse-breathing/).
So essentially, it is a protective mechanism my body adapted initially for specific occasions, and when occasions became frequent, the mechanism became a habit.

Unconsciously done, I wonder what  other habits and ways of life have we developed to protect ourselves from perceived threats in life - threats that even include feeling unsupported, uncertain, feeling stuck, or simply not knowing how to express ourselves? What has become natural to us, that we need to become unfamiliar with, so we can let go of that which has served its purpose to be?