|Attention Restoration Theory (ART) has been proposed as a potential approach to facilitate recovery from directed attention fatigue (DAF). The theory postulates directed attention is likely to replenish if permitted to ‘rest’. One way to allow directed attention to rest is to promote the use of involuntary attention. Previous research suggests viewing images of natural environments captures involuntary attention while simultaneously limiting the need for directed attention. However, in our failed attempt to replicate findings of previous research, along with shortcomings found within previous research, there remains uncertainty regarding the efficacy of an ART-based intervention. For example, ART-based interventions may be bound by certain conditions. Therefore, the purpose of this research was to investigate potential inter-individual factors that may moderate the relationship between greenspace and directed attention restoration. Specifically, research aimed to investigate the boundary condition of trait mindfulness in relation to the effects of walking while exposed to restorative stimuli (i.e., ‘green exercise’). The study examined whether trait mindfulness moderates the relationship between a 10-min bout of green exercise and attentional restoration from DAF. Results suggest that green exercise is inadequate for low or high trait mindful individuals’ directed attention restoration or superior attentional capacity and cognitive control. Data suggest that ART is questionable, even when considered within a theoretically-driven boundary condition.