Stress has evolutionary roots that help human beings evolve and survive. Existing workplace mental health models typically view stress as the direct cause of poor mental health. Such models focus on strategies to eliminate it. Guided by O’Connor and Kirtley’s integrated motivational-volitional (IMV) model, we posit that demanding jobs and high-stress environments do not directly impact an individual’s mental health but trigger a “sense of self” moderator (SSM), which then leads to mental health outcomes. This moderator is modified by the workplace’s organizational design and individual’s traits. We propose a Workplace Mental Health (WMH) Model, which suggests that by addressing these SSM modifiers through evidence-based interventions at organizational and individual levels, even in high-stress environments, organizations can have mentally healthy workforces and build high-performance workplaces. This paper assumes that stress is an inalienable part of any work environment and that a secular reduction in stress levels in modern society is infeasible. Although some individuals in high-stress job environments develop mental illness, many do not, and some even thrive. This differential response suggests that stress may act as a trigger, but an individual’s reaction to it is influenced more by other factors than the stress itself.