PurposeDue to lack of motivation, individuals often fail to perform regular exercise. In view of this, we developed a virtual trainer system (VTS) to encourage users to perform simple exercise routines regularly.Design/methodology/approachA design science approach is adopted to develop a VTS to motivate users to exercise. Study findings are based on a field experiment with 91 participants recruited from a university in Hong Kong.FindingsOutcome-oriented reminders foster stronger perceived risks of health and perceived value of exercises, whereas virtual trainer attractiveness has insignificant effect. Perceived value of exercises is positively related to exercise participation, which has a positive relationship with work productivity.Research limitations/implicationsThe findings answer question of how to motivate people to continue exercising.Practical implicationsFindings provide insights for fitness companies to design online exercise training for users.Social implicationsVTS can promote regular exercise and healthy life.Originality/valueThis research shows that interactive virtual agents can motivate users to exercise regularly. It contributes to the burgeoning research on the use of IT artifacts for improving exercise participation and provides practical insights into VTS designs.