The phrase "not know when to stop" implies an inability to recognize limits and boundaries, leading to excess and potential negative consequences. Some antonyms for this phrase could include words such as restrained, disciplined, measured, and moderate. These words suggest a sense of self-control and awareness of personal limits, allowing for appropriate and responsible behavior. Additionally, terms like judicious, reasonable, and prudent indicate a thoughtfulness and consideration in decision-making, highlighting the ability to recognize when to pull back and exercise discretion in one's actions. Overall, cultivating habits of restraint and moderation can lead to healthier relationships, improved productivity, and greater personal fulfillment.