Antonyms for the word "over-exerting" include "under-exerting," "underusing," "neglecting," "slacking off," "relaxing," and "taking it easy." These words imply a lack of effort, which is the opposite of over-exerting, which means to push oneself to the limit. The antonyms can apply in different situations, such as physical activity or mental work. For instance, while over-exerting oneself can lead to exhaustion or injury, under-exerting or slacking off can lead to poor performance or a lack of progress. Therefore, it is important to find a balance between exerting oneself enough to achieve goals without causing harm or burnout.