Arthur C. Brooks in The Atlantic:
Everyone—even the most privileged among us—has circumstances they would like to change in their life. As the early sixth-century Roman philosopher Boethius put it, “One has abundant riches, but is shamed by his ignoble birth. Another is conspicuous for his nobility, but through the embarrassments of poverty would prefer to be obscure. A third, richly endowed with both, laments the loneliness of an unwedded life.”
…Sometimes, changing your circumstances is difficult but absolutely necessary, such as in cases of abuse or violence. And sometimes, changing your circumstances is fairly easy: If you are lethargic every morning, start going to bed earlier. But in the gray areas in between, fighting against reality can be impossible, or incredibly inefficient. Maybe you have been diagnosed with a chronic illness for which there are no promising treatment options. Perhaps your romantic partner has left you against your wishes and cannot be persuaded otherwise. Maybe you have a job you like but a manager you don’t, and no one will give you a new boss.
In these sorts of situations, changing how you feel can actually be much easier than changing your physical reality, even if it seems unnatural. Your emotions can seem out of your control at the best of times, and even more so during a crisis—which is exactly when changing them would give you the greatest benefit. That can be blamed in part on biology. Negative emotions such as anger and fear activate the amygdala, which increases vigilance toward threats and improves your ability to detect and avoid danger. In other words, stress makes you fight, flee, or freeze—not think, What would a prudent reaction be at this moment? Let’s consider the options. This makes good evolutionary sense: Half a million years ago, taking time to manage your emotions would have made you a tiger’s lunch.