The antonyms for the phrase "being long lived" are brief, fleeting, and short-lived. Brief implies a short duration of time, while fleeting suggests something that passes quickly. Short-lived refers to something that only lasts for a limited period. The opposite of being long-lived can also be described as ephemeral, temporary, or momentary. These antonyms can describe many things, from a short-lived relationship to a fleeting moment of happiness. However, it's important to remember that just because something is short-lived doesn't make it any less valuable or meaningful. Sometimes, the most fleeting moments can be the ones that stick with us the longest.