When designing comfort and usability in products, designers need to evaluate aspects ranging from anthropometrics to use scenarios. Therefore, virtual and poseable mannequins are employed as a reference in early-stage tools and for evaluation in the later stages. However, tools to intuitively interact with virtual humans are lacking. In this paper, we introduceSmartManikin, a mannequin with agency that responds to high-level commands and to real-time design changes. We first captured human poses with respect to desk configurations, identified key features of the pose and trained regression functions to estimate the optimal features at a given desk setup. The SmartManikin's pose is generated by the predicted features as well as by using forward and inverse kinematics. We present our design, implementation, and an evaluation with expert designers. The results revealed that SmartManikin enhances the design experience by providing feedback concerning comfort and health in real time.