The phrase "kicking up heels" is often used to describe a lively, exuberant behavior or action. Its antonyms, on the other hand, refer to more subdued, restrained activity. Words such as "reserved," "subdued," and "calm" represent opposite states of mind to the excitement and enthusiasm implied by the original phrase. Antonyms for "kicking up heels" could also include terms such as "downplaying," "understated," or "muted." These words can be used to describe a state of relaxation or inactivity, or simply to indicate a more subdued or restrained behavior. Overall, the antonyms for "kicking up heels" represent the opposite of high spirits and exuberance.