Despite evidence that physical activity reduces the risk of falls and other causes of disability and death, the majority of older adults do not engage in physical activity on a regular basis. Mobile technology applications have emerged as potential resources for promoting physical activity behavior. This article describes features of a new application, Ready~Steady, highlighting approaches used in its design and development, and implications for clinical practice. Iterative processes enabled the design, development, implementation, and evaluation of the application consistent with the wellness motivation theory, as well as established user-specific strategies and theoretical design principles. Implications in terms of potential benefits and constraints are discussed. Integrating technology that promotes health and wellness in the form of mobile computer applications is a promising adjunct to nursing practice.