Acting listless can be a sign of exhaustion or a lack of motivation. If you want to express this concept with different words, there are several synonyms that you can use instead of "act listless." Some options might include feeling lethargic, lacking energy, seeming tired, apathetic, uninterested, indifferent, or disengaged. Other synonyms that might be appropriate could include feeling sluggish, appearing bored, unmotivated, or even depressed. Depending on the context of the situation, you can choose the right word that most accurately reflects the state of mind or behavior you want to convey.