I have no idea how stress works. Sometimes when I feel stressed out my watch says I am calm, other time when I feel engaged or not stressed the stress level is high.
For me, it was interesting that just changing my approach or story I use to interpret events can radically change the stress and lower it, without me feeling different. Physiologically something has changed, but on a conscious level I am still pissed or stressed.
This is the power of stories, they go deeper than our consciousness.