With the primary objective of human-robot interaction being to support humans' goals, there exists a need to formally synthesize robot controllers that can indeed provide the desired service. Synthesis techniques have the benefit of providing formal guarantees for specification satisfaction. There is potential to apply these techniques for devising robot controllers whose specifications are coupled with human needs. This work explores the use of formal methods to construct human-aware robot controllers to support the productivity requirements of humans. We tackle these types of scenarios via human workload-informed models and reactive synthesis. This strategy allows us to synthesize controllers that fulfill formal specifications that are expressed as linear temporal logic formulas. We present a case study in which we reason about a work delivery and pickup task such that the robot increases worker productivity, but not stress induced by high work backlog. We demonstrate our controller using the mobile Toyota Human Support Robot. The results demonstrate the realization of a robust robot controllers that is guaranteed to properly reason and react in collaborative tasks with human partners.