Abstract This study investigates the phenomenon of "endless motivation"—defined as continuous, high-intensity intrinsic and extrinsic drive—and its impact on employee performance. While motivation is traditionally viewed as a linear driver of productivity, this paper explores the psychological and physiological boundaries of sustained optimization. Using a quantitative survey of 300 corporate employees, the research analyzes the tipping point were continuous motivation transitions into occupational burnout. The findings indicate that while endless motivation initially spikes performance, it yields diminishing returns over time due to cognitive fatigue. Striking a balance between high drive and structured recovery is essential for long-term organizational productivity. This study investigates the psychological and behavioral trade-offs between sustained motivation and cognitive fatigue in the modern workplace. While organizational leadership frequently champions "sustained drive" to maximize output, cognitive psychology suggests that human attentional resources are finite. This empirical analysis examines whether high levels of continuous motivation can buffer the negative impacts of cognitive fatigue on employee performance, or if it accelerates burnout. Utilizing a mixed-methods approach, we tracked 250 corporate professionals over a six-month period, measuring daily motivational indices, cognitive workload, and objective performance metrics. The results reveal a non-linear relationship: continuous motivation successfully sustains performance under moderate fatigue, but crashes sharply past a critical cognitive threshold. These findings challenge the corporate ethos of perpetual hustle and offer a new framework for sustainable productivity.