I don't know how ChatGPT works, but it often feels like it is making inferences from data and those inferences are reasonable sounding but ultimately incorrect. In this case, it would be conflating work with workout. In one of my experiments, I was asking it about something in a children's book. ChatGPT ended up mixing up something that happened early in the story with something that happened at the end of the story, even though they were unrelated.

Climbing a staircase requires the same amount of work as climbing a down-escalator. The escalator "wants" to accelerate when you do work on it, but instead this work gets dumped into the braking mechanism, in order to maintain a constant speed.