Addiction & Recovery

Means just what it says, you make it one day at a time nothing really to do with the past except in the context of you are trying to quit using whatever your drug of choice happens to be and you are doing it one day at a time some times it comes down to one hour or even one minute at a time, whatever it takes to accomplish your goal of sobriety of freedom from whatever drugs you prefer.
It does not preclude planning ahead at all but planning to much can overwhelm your program so it needs to be kept within a small range, failures to meet goals can jeopardize your entire program by failing to meet goals. So the KISS procedure is best (Keep It Simple Stupid)