An unhealthy lifestyle is one of the key factors of mortality in modern society. Persuasive technologies, information systems that aim to change users behaviors and attitudes in a predefined way, are increasingly used for health promotion to encourage a physically active lifestyle and healthful nutrition to prevent diseases of affluence. Persuasive technologies for health come in different shapes, though, recent advances in mobile and sensor technologies have given rise to wearable self-tracking devices that have shortly reached high penetration in mainstream markets. While high hopes lie on persuasive technologies to improve personal and public health outcomes and empirical evidence for their effectiveness exists, concerns regarding their capacity to sustainably induce changes in health behaviors are growing. Despite the rich body of literature on the adoption of persuasive technology, gaps in knowledge exist with regard to users post-adoptive use experiences and behaviors, the processes along which persuasive technologies generate cognitive-affective and behavioral outcomes, and how persuasive technologies can impel such processes in a targeted way. This cumulative dissertation addresses these gaps and seeks to gain an understanding of post-adoptive use processes, to explain the occurrence of adverse experiences and their effects on users, to explain the outcomes of persuasive technology use, and to generate design knowledge to develop persuasive technologies to achieve long-term changes in health-promoting behaviors. These research objectives are achieved through eight research papers using different research approaches to shed light at different aspects concerning the post-adoptive use, the behavioral outcomes, and the design of persuasive technologies, by applying qualitative and quantitative research methods, and following the design science research paradigm. The dissertation makes several primary contributions to persuasive technology research: First, users habit formation processes and adverse experiences are highlighted. Second, the outcomes of persuasive technology use are outlined and mechanism-level explanations for why some users arrive at behavioral outcomes while others do not are provided. Third, by presenting a design artifact, design knowledge for the development of adaptive persuasive technologies for health promotion is generated. Moreover, the findings have important implications for practitioners, in particular, providers of persuasive technology and system designers.