Three studies examine the effects of exposure to nature on positive affect and ability to reflect on a life problem. Participants spent 15 min walking in a natural setting (Studies 1, 2, & 3), an urban setting (Study 1), or watching videos of natural and urban settings (Studies 2 & 3). In all three studies, exposure to nature increased connectedness to nature, attentional capacity, positive emotions, and ability to reflect on a life problem; these effects are more dramatic for actual nature than for virtual nature. Mediational analyses indicate that the positive effects of exposure to nature are partially mediated by increases in connectedness to nature and are not mediated by increases in attentional capacity. The discussion focuses on the mechanisms that underlie the exposure to nature/well-being effects. (Contains 7 tables and 4 notes.)