As far as science has come there is still an incredible amount we don't understand about the human body. The brain, personality and their related mechanisms are still one of the biggest mysteries.
Science Daily brings us an article titled "Rare Neurons Enable Mental Flexibility"
Scientists have recently been able to define an interneuron in the brain that effects mental flexibility. This is essentially the ability to "roll with the punches." The rats in the experimental group had toxins applied to these neurons to ensure they did not function. In the tests the experimental rats showed a lack of willingness to change their routines.
"While normal rats quickly responded to the light, rats with damaged neurons could not. The latter group continued to repeat the strategy they had already learned, and were disinclined to explore what the light meant."
This leads the researchers to believe these are the neurons associated with the willingness to explore and adventure. The degeneration of the brain with age may also explain why you "can't teach an old dog new tricks." This shows how little we still know about the brain but every single advancement we make is more astounding than the last.
The only thing inhibiting your appreciation of the human body and all of its astounding mechanisms is lack of knowledge. Sift through the educational resources we have to offer and begin to know what you don't even know.