It's rather irritating to break your own rule. To draw a line in the sand and then cross it. Of your own free wheel. Knowing the whole time that you're a mug for doing so. Yet, you still do it. (You, of course = me here.) I stupefy myself when I do something so silly. Which is why I try not to. But, sometimes, I still do it, even though I know better. Which is even more stupefying.
Even worse than that is, while you are breaking your rule, you are trying to convince yourself this isn't such a bad idea after all. It will be fine. Pleasant, actually. It will all work out. You'll see. This pep-talk goes on for the entire walk/wait/drive that is required to fully dismember the rule. Usually, it's quite a long walk/wait/drive, so you have plenty of time to perform this convincing. And it starts to work! You really start to believe that you were wrong for thinking this was wrong and soon you'll see it will all be all right! Hurrah for you! Stupid.
Then you get there. You step around the remnants of the broken rule, minding their sharp edges. Noting the mess you think, "Merde. I was right the first time. This was a stupid fricken idea and I'm a fricken idiot for not listening to myself. [Insert "again" here if it applies.]" Hopefully, though, you are not actually talking to yourself. Or at least not loud enough that others can overhear.
You go ahead and try to make the best of it. After all, you are already there and the rule is already broken. Rules, by the way, share the same DNA as Humpty Dumpty and once they are busted up, the king's horses and men can't help you pick up the pieces. You have to live with it.
At first, it's a total FAIL. You aren't enjoying yourself. It's miserable. You seriously consider cutting your losses and going back home, kicking yourself along the way. But, if you happen to suffer from pride of the stubborn variety, you will stick it out. You haven't walked/waited/drove all that way just to go back now. Stupid.
But then, the worst of the worst happens. You start to feel the situation soften. You ease into it. The next thing you know, you are smiling. Crap. You are actually having a good time. Now you are glad that you broke that silly rule and kick the scraps of it under the table...making it all the more easy to break another one in the near future.
But, because you don't want to think of yourself as stupid or silly, you reflect on that long walk/wait/drive home. While it might have worked out this time, that's no guarantee the next time you cross that line it will work out so well. Of course, this argument would be much more effective without that dopey grin on your face.