Content Warning: This section of the guide includes discussion of mental illness, death by suicide, self-harm, substance use, addiction, and death.

Harris introduces the fundamental paradox that makes sustained happiness difficult to achieve in modern life. The chapter establishes that human existence inherently involves both positive and negative experiences, with individuals experiencing moments of joy and achievement alongside periods of struggle and disappointment.

Harris presents statistical evidence to demonstrate that psychological distress is widespread. According to data from the World Health Organization (WHO), clinical depression affects one-tenth of adults annually and one-fifth of adults during their lifetime. Additionally, anxiety disorders impact one-third of adults at some point, while substance misuse affects one-fourth of the adult population. Most strikingly, Harris notes that nearly half of all people consider suicide for an extended period, with one-tenth attempting suicide.

The author traces the origins of human psychological distress to evolutionary adaptations from 300,000 years ago. The survival of early humans depended on their ability to anticipate and avoid dangers, leading to the development of minds that constantly assess potential threats. In modern times, this vigilance manifests as persistent worrying about various scenarios that may never materialize.