Many analyses and reviews have concluded that, at least for some individuals in some circumstances, exposure to nature can lead to improvements in multiple mental and physical health parameters and that this applies for both contemplative and adventurous activities (1–15). Over at least the past 4 decades, countries have trialed a wide range of public health programs aimed to increase public participation in outdoor activities, including visits to parks (14–18). At the same time, however, social and technological changes have created opposing pressures: education, work, and lifestyles in developed nations have become increasingly urbanized and indoors (19). Perhaps, as a result, these public health programs have achieved only limited success to date.