Rules were made to be broken?

The most difficult part of trading is the struggle to control yourself. It doesn’t seem like it would be hard to follow simple rules, but it turns out to be extremely difficult. I am not sure exactly why it is so hard - I am trying to figure this out. Today I overtraded and broke my rules again and lost more money than I should have. And I did this less than a couple of weeks after I swore never to do it again.
Part of the reason is that I was in profit and comfortable, so I was not as careful as I should have been.
A lot of the reason is just carelessness. I just broke a rule without hardly thinking about it. And this made it very easy to continue breaking rules. Suddenly, all rules are being broken and I know it. But it is very hard to stop once you get going. It is a mess. It looks bad. It feels bad. I’m embarrassed to admit it. I’m ashamed.
It gets me down at around 4pm when the market closes. It’s like waking up the morning with a hangover, realizing mistakes you made the night before. You feel horrible. But after an hour of thinking about it and developing a plan to make sure it doesn’t happen again, I pretty much get over it.
I try to beat myself up enough so that I learn as much as I can about it, but not enough to affect my trading or life.
But if this continues, I may have to take some time off and seriously consider what is wrong.