The seated position in our daily computer interactions has been identified as a major threat for health. Active workstations have been proposed as a healthy solution to these problems. However, research findings on the effects of such workstations on users’ productivity is not conclusive. We argue that physical demand and task difficulty play a role in influencing IT users’ performance and perceptions when using active workstations. An experiment manipulating task difficulty, direct and indirect physical demands was performed. Results suggest that task difficulty moderates the relationships between physical demand (direct and indirect) and users’ perceptions and performance. Findings will help organizations and employees determine if it is appropriate for them to use active workstations.