The humanoid was masterminded by the Bristol Robotics Laboratory, who tested Pepper on 10 people at a gym at the University of the West of England (UWE Bristol).
The participants, who were of all ages, came in three times a week for a total of three months to workout with Pepper to complete the NHS Couch to 5K programme.
They worked with two versions of the robot, one gave instructions every 30 seconds and the other had been give information from a real-life fitness instructor.
Overall, the participants preferred the more human-like option.
Robot expert, Katie Winkle, said: "Understandably, they weren't sure what to expect and when they started it was a bit of novelty.
"Some were energised by the robot and pushed themselves more than normal, and our fitness instructor was impressed with what the robot had learned to do.
"As time wore on, the participants began to treat the robot as a companion and the fitness instructor saw the robot as a colleague.
"This is really promising when we think about how robots might be used in the workplace in the future to work alongside humans."