The difference between a meaningful life and a meaningless life is Action. Action being taken, specifically, towards a connection with something greater than ourselves.
If, in the moment, no particular Action is being taken to experience “higher consciousness” or “state of Grace” or “God” or whatever you’d like to call it, Life is without meaning.
Actually, life is always having meaning. It’s just not so obvious when the person living it is not taking Action towards something greater than his or her self.