Some people are more resilient than others. They're able to deal with the traumas of life and bounce back stronger than ever. Research from scientists at the University of Michigan proves that emotionally resilient people are kinda, sorta, naturally high. From Science Daily:
The findings, recently published in Molecular Psychiatry by a University of Michigan Medical School team, show that the brain's natural painkiller system responds to social rejection — not just physical injury.

What's more, people who score high on a personality trait called resilience — the ability to adjust to environmental change — had the highest amount of natural painkiller activation.
What the.. So when these people run into a mess of bad juju, they're instantly rewarded with brain painkillers?! Where was mine? Damn you, brain.