Other forms: seizing the day; seized the day; seizes the day
To seize the day is to make the most of the present moment. It's a phrase that urges you to act now, take opportunities that present themselves, and enjoy life while you can.
Seize the day is a translation of the Latin carpe diem, which was popularized by the Roman poet Horace around 23 BCE. Carpe means "pluck or harvest," and diem means "day." The full phrase in which it was originally used translates to "Seize the day, trusting as little as possible in tomorrow." In other words, live to the full right now, as you never know what tomorrow will bring. Seize the day!