The antonyms for the phrase "doeth one's best" could include "half-hearted effort," "slacking off," "taking shortcuts," "not giving one's all," or "doing the bare minimum." These antonyms suggest a lack of dedication, motivation, or commitment to the task at hand. Choosing to not do one's best can result in subpar results or a lack of success. It's crucial to put in effort and focus on doing one's best to achieve maximum results. Avoiding the antonyms of "doeth one's best" and striving for excellence can lead to a greater sense of accomplishment, confidence, and admiration from others.