> personally avoid to think about my self with labels about what "immutable" things "I am". Like "he is tall", "he has Z skin color", "he has 9 fingers", "he has brain type X", "he is thin", etc.

So do I, but when one attempts to push a square peg through a round hole (and sufficient force applied), the structural integrity of the square peg is compromised.

This is to say, if working against your inertia becomes traumatically painful, you may in reality be working against your nature rather than your inertia.

It requires a certain wisdom and a great deal of experience to distinguish between those aspects of oneself are immutable vs mutable. But I believe firmly that a loosely-held understanding of one's immutable nature is highly useful in living a happy life. I consider it equally important to what you are getting at: that some aspects which appear to be immutable are actually not, and the only way to know for sure is to stretch outside of one's comfort zone.

It takes skill and experience to tell the difference, but the effort is worth it.