The objective of the research was to determine the effect of mental load on the physical capacity of an individual. An experiment involving 9 combinations of lifting tasks, 1 lowering task, and 3 treadmill tasks was conducted. Heart rate was measured and maximum acceptable weight of lift was determined using the psychophysical method. A simple multiplication task was used as the mental load. The output variables were determined with and without the mental task. The results indicate that the individual's physical capacity decreased with the mental task while lifting from floor to knuckle and shoulder to reach lifting heights.