Running out of steam is a common phrase to describe a person or thing's energy or momentum dwindling. However, it is not the only phrase used to describe this phenomenon. Other synonyms include "losing momentum," "hitting a wall," "running low on fuel," "sputtering out," and "losing steam." All of these phrases suggest a gradual or sudden loss of energy, whether it be physical or metaphorical. It is important to vary the language we use to describe such situations to avoid repetition and keep our writing or speaking engaging and interesting. By using synonyms, we can provide a more accurate and nuanced representation of what we are trying to convey.