Many people who have successfully overcome addictions of all forms have found that it's much easier to accomplish if they have a "one day at a time" attitude. They say, "Just for today I will refrain from a counterproductive habit or pattern." We don't need to be totally certain that it will never happen again, just that it's not going to happen today.

We live our entire lives one day at a time, so we only need to commit to today. It's always just today. So someone who is sincere about refraining "just for today" has the necessary tool not to engage in a counterproductive behavior.

This same idea can also be beneficial in engaging in a positive habit or life-improving pattern that is difficult to implement. Right now, it might seem like climbing the tallest mountain to think that we will always do the positive thing. But "just for today" seems easier and more practical. Just as we can only breathe taking one breath at a time, anything positive we will do we can only happen "today."
Encouraging just "one day at a time" is often more practical than thinking right now about doing or not doing something "all the time." Some people love this idea and have found it highly beneficial. If you like the idea and "just for today" works for a specific person you want to motivate to do or not do something, then apply this approach as you offer encouragement.