If you’re like many Americans, you probably start your day with a cup of coffee – a morning latte, a shot of espresso or maybe a good ol’ drip brew.

A common explanation among avid coffee drinkers is that we drink coffee to wake ourselves up and alleviate fatigue.

But that story doesn’t completely hold up. After all, the amount of caffeine in a cup of coffee can vary wildly. Even when ordering the same type of coffee from the same coffee shop, caffeine levels can double from one drink to the next. And yet, we coffee drinkers don’t seem to notice.

So what else might be driving us in our quest for that morning brew?

That’s one question we set out to answer in our recent research. The answer has far-reaching implications for the way we approach major societal challenges such as diet and climate change.

As behavioral scientists, we’ve learned that people often repeat everyday behaviors out of habit. If you regularly drink coffee, you likely do so automatically as part of your habitual routine – not just out of tiredness.

But habit just doesn’t feel like a good explanation – it’s unsatisfying to say that we do something just because it’s what we’re used to doing. Instead, we concoct more compelling explanations, like saying we drink coffee to ease our morning fog.

This reluctance means that we fail to recognize many habits, even as they permeate our daily lives.

Unpacking what lies behind habits

To test whether people underestimate the role that habit plays in their life, we asked more than 100 coffee drinkers what they think drives their coffee consumption. They estimated that tiredness was about twice as important as habit in driving them to drink coffee. To benchmark these assumptions against reality, we then tracked these people’s coffee drinking and fatigue over the course of one week.

The actual results starkly diverged from our research participants’ explanations. Yes, they were somewhat more likely to drink coffee when tired – as would be expected – but we found that habit was an equally strong influence. In other words, people wildly overestimated the role of tiredness and underestimated the role of habit. Habits, it seems, aren’t considered much of an explanation.

We then replicated this finding in a second study with a behavior that people might consider a “bad” habit – failing to help in response to a stranger’s request. People still overlooked habit and assumed that their reluctance to proffer help was due to their mood at the time.

The gap between the actual and perceived role of habit in our lives matters. And this gap is key to understanding why people often struggle to change repeated behaviors. If you believe that you drink coffee because you are tired, then you might try to reduce coffee drinking by going to bed early. But ultimately you’d be barking up the wrong tree – your habit would still be there in the morning.

Why habits are surprisingly difficult to change

The reason that habits can be so difficult to overcome is that they are not fully under our control. Of course, most of us can control a single instance of a habit, such as by refusing a cup of coffee this time or taking the time to offer directions to a lost tourist. We exert willpower and just push through. But consistently reining in a habit is fiendishly difficult.

To illustrate, imagine you had to avoid saying words that contain the letter “I” for the next five seconds. Pretty simple, right? But now imagine if you had to maintain this rule for a whole week. We habitually use many words that contain “I.” Suddenly, the required 24/7 monitoring turns this simple task into a far more onerous one.

We make a similar error when we try to control unwanted habits and form new, desirable ones. Most of us can achieve this in the short run – think about your enthusiasm when starting a new diet or workout regimen. But we inevitably get distracted, tired or just plain busy. When that happens, your old habit is still there to guide your behavior, and you end up back where you started. And if you fail to recognize the role of habit, then you’ll keep overlooking better strategies that effectively target habits.

The flip side is also true: We don’t recognize the benefits of our good habits. One study found that on days when people strongly intended to exercise, those with weak and strong exercise habits got similar amounts of physical activity. On days when intentions were weaker, however, those with strong habits were more active. Thus, strong habits keep behavior on track even as intentions ebb and flow.

It’s not just willpower

American culture is partly responsible for the tendency to overlook habits. Compared with residents of other developed nations, Americans are more likely to say that they control their success in life.

Accordingly, when asked what stops them from making healthy lifestyle changes, Americans commonly cite a lack of willpower. Granted, willpower is useful in the short term, as we muster the motivation to, for example, sign up for a gym membership or start a diet.

But research shows that, surprisingly, people who are more successful at achieving long-term goals exert – if anything – less willpower in their day-to-day lives. This makes sense: As explained above, over time, willpower fades and habits prevail.

If the answer isn’t willpower, then what is the key to controlling habits?

Changing habits begins with the environments that support them. Research shows that leveraging the cues that trigger habits in the first place can be incredibly effective. For example, reducing the visibility of cigarette packs in stores has curbed cigarette purchases.

Another path to habit change involves friction: in other words, making it difficult to act on undesirable habits and easy to act on desirable ones. For example, one study found that recycling increased after recycle bins were placed right next to trash cans – which people were already using – versus just 12 feet away.

Effectively changing behavior starts with recognizing that a great deal of behavior is habitual. Habits keep us repeating unwanted behaviors but also desirable ones, even if just enjoying a good-tasting morning brew.

Wendy Wood receives research funding from National Institute on Aging, Centers for Disease Control and Prevention.

Asaf Mazar does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.