The purpose of this study was to test the association between lifestyle-related modifiable health risks (physical activity, cardiorespiratory fitness, and obesity) and work performance. Data were obtained from 683 workers. Dependent variables included number of work loss days, quantity and quality of work performed, overall job performance, extra effort exerted, and interpersonal relationships. Results indicated that higher levels of physical activity related to reduced decrements in quality of work performed and overall job performance; higher cardiorespiratory fitness related to reduced decrements in quantity of work performed, and a reduction in extra effort exerted to perform the work; obesity related to more difficulty in getting along with coworkers; severe obesity related to a higher number of work loss days. It is concluded that lifestyle-related modifiable health risk factors significantly impact employee work performance.