Walking in nature has been demonstrated to have a positive impact on cognitive and emotional wellbeing by restoring attention and increasing positive affect. Both of these factors are in turn linked to increases in flexible, reflective thinking ("broadened thinking"). Broadened thinking is contrasted to the narrowing of thoughts associated with scarcity, the experience of having less than one feels is necessary. This study proposed a new model outlining the process by which broadened thinking may occur during nature walks and, for the first time, incorporated the experience of scarcity into the nature walk literature. One hundred sixty-five college students reporting varying levels of perceived scarcity were randomly assigned to one of two conditions (natural or built) and took a 30-minute walk in an environment of their choosing. Structural equation modeling demonstrated that the proposed model was a good fit for the data. This supports the hypothesized process linking nature walks with restoration of attention, positive affect, and broadened thinking. Qualitative data corroborated these findings. Although scarcity did not moderate relationships in the model as expected, repeated measures ANOVA results showed that participants experiencing the highest time scarcity saw the greatest increases in restoration and broadened thinking. Those with the highest material scarcity saw the greatest increases in motivation to engage in subsequent walks. These findings provide some support for the hypothesis that those with more scarcity would derive greater benefit from nature walks. The study as a whole demonstrates the effectiveness of nature walks as a brief intervention for college students, especially those pressed for time, and highlights the importance of cultivating and protecting natural walk environments that are safe and accessible for all. Implications for future research and clinical interventions at the individual and societal level are discussed.