This chapter examines the critical role of functional and mobility training in enhancing the operational performance and resilience of the human weapon system (HWS). The authors emphasize the importance of tailored fitness regimens that address the unique physical demands of tactical, first responder, law enforcement, and firefighter professionals, integrating functional fitness to improve strength, agility, flexibility, and balance. Mobility training is explored as a dynamic and integrative approach to ensuring effective movement patterns and mitigating injury risks. The chapter provides a framework for incorporating flexibility, range of motion (ROM), and mobility into training programs alongside tools like functional movement screening (FMS) and the Y-Balance Test (YBT) for assessment and injury prevention. With practical methodologies and collaborative approaches involving the entire human performance team, this chapter offers actionable insights to develop effective, sustainable mobility programs that enhance performance and physical health in high-stress environments.