Updated: Oct 23, 2020
You vow you'll never do THAT again (whatever THAT may be) because the wound (the undesirable result of THAT) is fresh and now you're suffering. But, the sad truth is you'll probably do THAT again soon and you may even do THAT again before the day is over.
And you're not dumb. Other people have called you out on this before. You've been in therapy. You know exactly what the problem is and yet can't seem to change THAT.
Here's an example from my life: I tend to run late. For almost everything. I'm not usually more than five or ten minutes late for important things, but I'm rarely more than a minute or two early.
In all fairness, can I say I'm "punctuality-challenged" because I have ADHD? Well, yes and no. Yes, in the sense that ADHD impairs my executive functions and therefore I don't plan ahead as well as most people. But, on the other hand, since I'm usually late by say, 7.5 minutes on average, I'm consistently planning ALMOST correctly. So something more than just ADHD is at work here.
The reason I tend to arrive at places 5-10 minutes late is BECAUSE I USUALLY GET AWAY WITH IT. I'll call this simple explanation "rat theory." If a rat in a maze USUALLY gets cheese when it performs certain actions, it will continue to do them. It's instinctive and automatic. Similarly, like the rat, I keep being just a wee bit late for things because my lateness USUALLY is a non-issue and I still reap the rewards of participating in whatever event I've just managed to quietly sneak into.
Do I ever get flak from others because I'm late? Rarely. I tend to preempt any resentment I might encounter by acknowledging my tardiness before anyone can point at their watches -- "I know I'm late, so sorry...traffic was a beast." Is it embarrassing? Yes. Do I berate myself for it? All the time. But, guess what -- berating myself each time I'm late isn't enough to change the behavior. I'm so used to being embarrassed by lateness and feeling bad about it that I'm IMMUNE to it. It's a temporary feeling that goes away soon after I experience it.
However, what would change this pattern completely is if I knew with certainty that if EVERY TIME I'd arrive as much as a minute late for something, WITHOUT EXCEPTION, I'd be publicly rebuked and sent home, I would NEVER be late again. And neither would you if you're time-challenged like me.
So...getting back to why you're still doing THAT thing you know is hurting yourself or others -- you don't stop because you USUALLY get away with it. And, let's face it, there's always some small reward attached to the self-defeating behavior. (In my case, my reward is an [imaginary] extra twenty minutes to sleep, read, etc.. before I get ready to go where I'm going.)
So, don't blame THAT thing you keep doing on your ADHD. Not entirely, anyway. And it's not about not knowing any better. Of course you know better. You'll only change when (and if) the pain of continuing to do THAT becomes greater than the rewards you're still reaping (at least occasionally) from doing THAT.