Yes indeed, many of us do. Nearly everyone I've ever dated gets mad at me at some point because I can't keep cookies in the house or I will eat them all. You are far from alone, and in fact I suspect the overwhelming majority of people are the same. Hence the obesity epidemic.

Personally I find that my self-control is limited to the same extent that my time and energy are limited. If I'm tired, it's harder for me to be disciplined, and the place that I most often tired is at home at the end of the day, when temptation to over eat is at the greatest. I believe there is a fairly substantial body of evidence that shows I am not unusual in this regard. This phenomenon is why groceries stores put candy in checkout lanes, when you are mentally tired from exercising discipline by not picking up the delicious-looking tray of cupcakes in the bakery aisle and thus are most susceptible to temptation.

I think some people can just use willpower to maintain their discipline in every situation, but those people are extreme outliers. Like Navy SEALs or Olympic athletes or other extreme high performers, and not even all of them. Those who can are experts at delayed gratification and are able to visualize what they want and then never deviate from their plan for how to achieve it, regardless of their current emotional state or energy levels. But that is vanishingly rare and often their behavior is a result of some deep trauma (eg someone who is super disciplined about their diet because their dad died early from an obesity-related illness) rather than a positive focus on a certain outcome. The truth is that the vast majority of people just follow their natural inclinations and do whatever is easiest for them. The path of least resistance.

As one such weak-willed person, my approach has been to structure my life to remove temptations, much as the GP comment above described their approach to curating their internet content. For example, I have lived almost exclusively in big cities for my entire life until the last year, when I moved to the middle of nowhere. Which means I can't get takeout food delivered and it's much harder to go out and get ice cream on a whim. Compared to living in a major city where I could get Michelin star restaurant food delivered in a matter of minutes, the temptation is just much, much less powerful. I order my groceries online too, which also dramatically reduces the tendency to impulse buy anything unhealthy (I get to skip the checkout lane with the candy, for one thing). On the other side of the caloric equation, I set up a home gym so that travel time to the gym doesn't become an excuse not to exercise. Basically I add barriers for bad choices and remove them for good ones. I am in the best shape of my life as a result.

I guess what I'm saying is that most people achieve good behaviors in part because of their intentional discipline and in part because their environment is conducive to those behaviors. The real trick is figuring out how to intentionally structure your environment to match whatever behaviors you want. It's effectively borrowing motivation from your peak-energy level periods to provide discipline during periods when you don't have the energy to generate it yourself. It can be incredibly hard to figure out, because you need to know how to change your environment and how you will actually react to that new environment, which isn't always predictable.