The phrase "am on feet" is typically used to describe standing or being upright. The antonyms for this phrase could include words such as sitting, lying down, or being horizontal. When someone is not on their feet, they may be in a relaxed or more comfortable position, such as sitting in a chair or laying on a bed. This can be helpful for people who need to rest or recover from physical activity or injury. In contrast, being on one's feet for prolonged periods of time can cause discomfort or strain, making it important to take regular breaks and shift positions throughout the day.