seize the day \seez the dey\ To enjoy the present and not worry about the future; to live for the moment. To make the most of today by achieving fulfillment in a philosophical or spiritual sense. See: Newsies.
you on·ly live once \ˈyü ˈōn-lēˈlivˈwən(t)s\ What YOLO actually stands for. I know the phrase is five whole syllables instead of two, but I strongly recommend saying this instead as to not look and/or sound like a fool.