Antonyms for the phrase "gotten a workout" could refer to the opposite of physical exertion or activity, such as being sedentary or inactive. Words like "rested," "relaxed," "unstressed," or "unchallenged" may fit the bill in this case. Another antonym could refer to a lack of stimulation or challenge, suggesting that something has remained untested, unchallenged, or underutilized. Phrases like "unused," "underworked," or "neglected" could apply here. Overall, the antonyms for "gotten a workout" suggest a state of calm, ease, and minimal effort, opposed to the intense activity and exertion that the original phrase implies.