Regular physical exercise and decreasing sedentary behavior are essential for the health of adults [1]. However, even with well known benefits, in 2016, it was determined that the prevalence of insufficient physical activity in the world population was 27.5% [2]. In this paper, we utilized a humanoid robot as an instructor for physical exercise in a stationary bicycle. By applying questionnaires as well as recording sensor data, we measured the impact of the robot in the motivation and other psychological aspects, as well as the performance in 14 participants. The participants were males and females with an average age of 23.5 ± 2.38 years, and were equally and randomly divided in two groups: one with the robot instructor, and a control group. They performed two exercise sessions, after which they answered the questionnaires. The results were not statistically significant (p <; 0.05), but show a trend of the robot having a positive impact in the group that interacted with it, regarding their motivation, pleasure and enjoyment. The interaction also seems to have positively influenced the mood of the participants. The perceived effort, as well as average speed and cycled distance did not seem to have been influenced by the robot. Future studies, with a larger sample size, are needed to confirm the trend shown here.