The psychological phenomenon of hedonic adaptation, often called the “hedonic treadmill,” provides important psychological context for the central problem The Gap and the Gain aim to solve: why highly successful people often feel unfulfilled. This principle describes the human tendency to return to a baseline level of happiness, regardless of major positive achievements. As Psychology Today explains, “The hedonic treadmill is the observed tendency of humans to quickly return to a relatively stable level of happiness despite major positive or negative life events. We work hard to achieve a goal, anticipating the happiness it will bring, but the thrill of achievement quickly wears off” (Fagan, Abigail. “Hedonic Treadmill.” Psychology Today, 12 Nov. 2025). This innate tendency to normalize success helps explain why the book portrays chasing a future “Ideal” as a source of ongoing dissatisfaction.

Sullivan and Hardy frame the “GAP” mindset as closely reflecting this treadmill. The book’s example of the entrepreneur Edward who constantly moves his financial goalpost from $5 million to $10 million and beyond, illustrates this cycle. Each achievement provides no lasting satisfaction because he quickly adapts to his new level of success, and a new, more distant ideal immediately takes its place. The authors present that the “GAIN” as a way of counteracting this treadmill. Instead of pursuing ever-receding future goals, measuring backward anchors satisfaction in past progress, encouraging readers to recognize how far they have come rather than how far they still have to go. The book therefore presents this approach as a practical strategy for countering hedonic adaptation by changing how success is measured.