Academic Abstract People want to pursue happiness but often fail, a phenomenon known as the paradox of pursuing happiness. The mechanisms underlying this paradox remain elusive. Age differences in happiness—specifically that older adults appear more successful in pursuing happiness (the emotion paradox of aging)—provide valuable insights into effective happiness pursuit. Drawing on this literature, we propose an intergoal compatibility account to interpret both paradoxes through the lens of intergoal interactions, an intuitively critical yet underexplored factor in existing interpretations. This account asserts that greater compatibility (fewer conflicts and greater facilitation) between happiness pursuit and other important personal goals enhances the effectiveness of happiness pursuit, and such compatibility can be enhanced through contextual influences (e.g., age-graded developmental tasks) and strategic self-regulation (e.g., goal adjustments). This account generates testable predictions and practical implications for enhancing happiness pursuit across the lifespan. Public Abstract Why do people often struggle to achieve happiness? And why are older adults happier than younger adults, even though they face more losses in life? While these questions have drawn extensive attention, they remain puzzling. A crucial yet insufficiently explored factor in successful happiness pursuit is intergoal compatibility —the extent to which the pursuit of happiness aligns or conflicts with other important personal goals. For younger adults, the demands of age-related developmental tasks (e.g., educational and career aspirations) often create conflicts with the pursuit of happiness, diminishing its effectiveness. Conversely, in older adults, happiness becomes more prioritized and compatible with other important personal goals, thereby enhancing the effectiveness of pursuing happiness. A lesson we can learn from older adults is to pursue happiness in ways compatible with other important personal goals.