This experimental study evaluates the suitability of a social robot for inducing behavior change, where the robot serves as a behavior change coach. Using a simulation of the social robot Haru developed by the Honda Research Institute, this study measured the effect of the robot’s emotional expressions and behaviors on behavior change and the perceived quality of the session. The method for behavior change employed is the ‘Tiny Habits’ approach developed by (Fogg 2019), which assumes that behavior can be changed if a) the behavior to be changed is broken down into a tiny habit, b) this habit is anchored in the person’s everyday life, and c) every success is celebrated. Based on these principles, a scripted dialogue was created to coach participants in a session in which they chose a behavior they wanted to change themselves. The experiment proceeded with altogether 30 participants. In the experimental condition, the dialogue between participant and the robot simulator was interspersed with emotional expression and behaviors such as dancing, bowing and vocalizing. The control condition utilized the same setup with the robot simulator and provided participants with the same guidance, but without emotional expression. Our results reveal a positive effect of emotional behavior on most of the measured variables. Compared to the baseline, the participants in the emotional condition had a higher motivation to change their behavior, felt more confident in applying the behavior change method, confirmed that they would think differently about behavior change and rated the quality of the lesson higher.