Work-related musculoskeletal disorders are a majorhealth issue often caused by awkward postures. Identifyingand recommending more ergonomic body postures requiresoptimizing the worker’s motion with respect to ergonomicscriteria based on the human kinematic/kinetic state. However,many ergonomics scores assess different risks at different placesof the human body, and therefore, optimizing for only onescore might lead to postures that are either inefficient or thattransfer the risk to a different location. We verified, in two workactivities, that optimizing for a single ergonomics score maylead to motions that degrade scores other than the optimizedone. To address this problem, we propose a multi-objectiveoptimization approach that can find better Pareto-optimal trade-off motions that simultaneously optimize multiple scores. Oursimulation-based approach is also user-specific and can be usedto recommend ergonomic postures to workers with differentbody morphologies. Additionally, it can be used to generateergonomic reference trajectories for robot controllers in human-robot collaboration.