This episode explains why humans are surprisingly bad at affective forecasting, which is the process of predicting our future emotional states. We consistently fall victim to the "impact bias," overestimating both the intensity and the duration of the happiness a positive event will bring and the despair a negative event will cause. This occurs because we fail to account for our remarkable ability to adapt to new circumstances. We are more resilient than we think, but our inability to predict this resilience leads us to make poor decisions in pursuit of happiness. A primary reason for this flawed forecasting is our "psychological immune system," an unconscious set of cognitive processes that helps us synthesize happiness and find the good in our situations, especially after a negative outcome we cannot change. This system is more effective at dealing with major challenges than minor annoyances, which is why we can sometimes recover more quickly from significant setbacks than from small, persistent irritations. We rationalize our reality to protect our emotional well-being, but we don't anticipate this process when making future plans. This leads to the "arrival fallacy": the false belief that achieving a certain goal—like getting a promotion or buying a house—will result in lasting happiness. In reality, the emotional boost from such achievements is often fleeting as we quickly adapt to the new normal. True, sustainable well-being is found not in reaching specific destinations, but in the meaning and engagement derived from the process and the journey itself.