For me this was learning how subjective the human experience is from studying hypnosis.
Most of our physical experiences are defined by the stories we tell ourselves.
If someone tells you your feet are stuck to the floor and you subconsciously believe it, it is so.
A lifetime of chronic pain can vanish in an instant when your brain believes a different story, by for example a hypnotist telling you so.
This also portrays to our self-esteem and what we can accomplish in the world.
We put so many limitations on ourselves.
You don't know what you can't do.