Today, advances in wireless sensor networks are making it possible to capture large amounts of information about a person and their interaction within their home environment. However, what is missing is how to ensure the security of the collected data and its use to alter human behavior for positive benefit. In this research, exploration was conducted involving the "infrastructure" and "intelligence" aspects of a wireless sensor network through a Behavior Modification Sensor System. First was to understand how a secure wireless sensor network could be established through the symmetric distribution of keys (the securing of the infrastructure), and it involves the mathematical analysis of a novel key pre-distribution scheme. Second explores via field testing the "intelligence" level of the system. This was meant to support the generation of persuasive messages built from the integration of a person's physiological and living pattern data in persuading physical activity behavior change associated with daily walking steps. This system was used by an elderly female in a three-month study. Findings regarding the "infrastructure" or the novel key pre-distribution scheme in comparison to three popular key distribution methods indicates that it offers greater network resiliency to security threats (i.e., [Special characters omitted.] times lower), better memory utilization (i.e., 53.9% less), but higher energy consumption (i.e., 2% higher) than its comparison group. Findings from the "intelligence" level of the research posit that using a person's physiological and living pattern data may allow for more "information rich" and stronger persuasive messages. Findings indicate that the study participant was able to change and improve her average daily walking steps by 61% over a pre-treatment period. As the study participant increased her physical activity, changes in her living pattern were also observed (e.g., time spent watching television decreased while time spent engaged in walking increased by an average of 15 minutes per day). Reinforcement of these findings were noted between a pre and post-study survey that indicated the study participant moved from a "contemplation" stage of change where physical activity engagement was intended but not acted upon to an "action" stage of change where physical activity engagement dominated the new behavior. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]