The E&P industry has embarked upon a "Journey to Zero" in which SPE has taken a leading role. While "Zero" is a noble and worthy philosophical goal, this paper describes several practical challenges that exist in turning this aspiration into reality with respect to defining, measuring, attaining and sustaining such a performance. A realistic and defensible definition of "Zero" is offered that bridges the gap between aspiration and operational reality which potentially has application in all organizations on a "Journey to Zero".