This study involved examining the ability of a postadoption intervention to reduce returns of newly adopted dogs to shelters by encouraging physical activity between adopters and their dogs. Guardians in the intervention group received emails with dog behavior and human activity advice as well as invitations to join weekly dog walks. Both the intervention and control groups completed surveys regarding outdoor activity with their dogs, their dog-walking habits, and perceptions of their dogs’ behaviors. Adopter–dog pairs in the intervention group were not significantly more active than those in the control group, nor did they show a reduced incidence of returning their dogs. Guardians in both groups who reported higher obligation and self-efficacy in their dog walking were more active regardless of experimental condition; however, obligation, dog-walking self-efficacy, and perceptions about their dogs’ on-leash behaviors did not predict rates of return to the shelter. These findings add to the understanding of shelter dog re-relinquishment and the effective utilization of resources postadoption, and they indicate further research is needed to address the complexities of this newly forming human–dog relationship.