“Just this once.” It’s not just the matting call of adolescent boys everywhere, it’s the cue for new years resolutions to pack their bags and head to the Bahamas, they know they won’t be seeing you again.

This one little phrase can undo more momentum and cause more trouble than any other excuse, rationale or justification out there. I recently said this to my four-year-old son when he protested my proposed trip to Costco, as usual. He hates going there, as do I, and he throws a fit whenever I break that bad news that a visit is imminent. On this particular day he wore me down so I said to him “just this once we can skip it.” As soon as the words came out I realized I had made a big mistake. Now, not only does he throw an even bigger temper tantrum when I mention going, he’s busted out the phrase “just this once” a few times to try to persuade me or weasel out of doing something. What have I done?

We’ve all said this to ourselves for various reasons to enable ourselves to do or not do something. You know you shouldn’t sleep with your ex boyfriend but “just this once” can’t hurt. You’re trying not to drink during the week so that you can wake up early and go to the gym but its okay “just this once.” The next morning, after two weeks of consistent workouts you decide it would be okay to sleep late and not go “just this once.” Without awareness “just this once” turns into again and again and again.

Be aware, “just this once” has some good buddies. Their names are “I will start again tomorrow” and “I can stop at any time.” You don’t want to hang out with these guys, so don’t even entertain them in the first place.

Decide now that you will never ever allow yourself to engage “just this once” again. Your goals, self-esteem and thighs will thank you.