The phrase "works into lather" means to become agitated or worked up about something. The antonyms for this phrase would be to remain calm, composed, or relaxed. You could also say that someone is indifferent, dispassionate, or unaffected by a certain situation. Other antonyms could include being level-headed, unemotional, or stoic. In some cases, it may be necessary to use words such as quiet or still to describe the opposite of "works into lather." Overall, the antonyms for this phrase portray a sense of stability and control, contrasting with the frenzied and anxious tone that "works into lather" implies.