The phrase "brake one's back" means to work excessively hard or to exhaust oneself physically or mentally. Some antonyms for this phrase could include taking it easy, relaxing, being idle, or slacking off. These antonyms suggest a lack of effort or exertion, and are often associated with rest and leisure. Other antonyms could include working smart, pacing oneself, being efficient, or collaborating with others. These antonyms suggest the importance of balancing effort and rest, and imply that hard work can be done in a sustainable and effective way.
