Interesting article.

https://www.dana.org/Cerebrum/2014/One_of_a_Kind__The_Neurobiology_of_Individuality/

What processes in the brain are responsible for individuality? Mounting imaging evidence suggests that brain circuits involved in our emotional responses are highly plastic and change with experience, affecting our temperament. Moreover, new research suggests that psychological interventions can further harness brain plasticity to promote positive behavioral changes that increase resilience and well-being.

Although chronic pain isn't mentioned, it links resiliency to basal cortisol levels, personality type, neuroplasticity, and of course its effect on health.