OBJECTIVES: This study aimed to describe the implementation of a workplace health promotion to address low levels of physical activity (PA). METHODS: Using the Exploration, Preparation, Implementation, Sustainment (EPIS) framework, we implemented and evaluated a 10-week workplace step-count challenge to promote PA. All health system employees invited to participate. Data were collected on the exploration, preparation, and implementation phases. RESULTS: During exploration, we recognized inadequate PA among employees. Meetings with key personnel were held to determine details of the health promotion and obtain support. We pursued a step-count PA intervention, capitalizing on employee ownership of smartphones with accelerometers. Vendors to host the intervention were evaluated. All employees were invited to participate. Participants received weekly messages about improving PA and notifications of weekly challenges. Exit interviews provided feedback and suggestions. CONCLUSIONS: A workplace health promotion focused on employee PA is feasible using EPIS.