The psychological impact that robots have on workers in a physical human-robot collaboration is not well researched. This creates a risk of creating monotonous jobs for workers as more and more robots enter the workforce. To mitigate this risk, physical human-robot collaboration should be designed to have a positive psychological impact by facilitating a flow state. Flow is the experience of complete absorption into the current moment. Based on studies in other fields, a new method for designing a physical human-robot collaboration for flow has been developed. This new method was applied to an abstract blending task in which the robot assisted the human in blending. A controlled experiment was conducted to test the psychological impact that this design method had on participants. The findings provide evidence that designing for flow made the task more satisfying, as such indications were found that suggest participants were more motivated in their task, finding it more rewarding, causing them to do more of the task than required. However, no significant impact on flow was found because participants in the control group were equally focused as participants who had the task designed for flow. Nonetheless, the positive impact that designing the physical-human robot collaboration had on the motivation and satisfaction of the humans still created a positive psychological impact. This makes designing for flow a promising method for building towards a human-centered future of work.