"Now or never" is an idiom that refers to the need for decisive action at a specific moment. Other synonyms for this phrase include "seize the day", "carpe diem", "time is running out", "make a move", "grab the opportunity", "take the plunge", or "strike while the iron is hot". These phrases all suggest a sense of urgency and the need to act promptly and decisively. They advise us not to waste time and to take advantage of every opportunity that comes our way. So, whether it's pursuing our dreams, taking a chance on love, or chasing our goals, these phrases remind us that the time for action is now, or it may never come again.