In her new book, Good Habits, Bad Habits, USC professor of psychology and Behavior Change for Good Initiative team scientist Wendy Wood teaches us how habits are formed. She breaks down the mechanisms that put our brains on autopilot—for better or worse—and tells us how to start fighting back. What can we do to break the habits that are keeping us from saving money, exercising, and generally living fuller, healthier lives? Wood explores all of this in her book and tells us how to form habits for the better.

Wood shared her wisdom on a recent episode of Choiceology, a podcast hosted by Wharton professor and BCFG director of savings and health Katy Milkman. The following is excerpt from the interview.

Katy Milkman: I want to start by just asking a really basic question. What is a habit? 

Wendy Wood: That’s actually a very good question to start with because it’s not something we intuitively understand. When we repeat a behavior over and over and get a reward for it our minds learn over time to associate what we’ve done with the context in which we got the reward. So habits are a kind of a shortcut.

Imagine the first time you walked into your kitchen in the morning and started to make coffee. You had to think about what to do. But over time, if you do it enough, making coffee becomes a habit. It becomes something you can do without even thinking. You walk into your kitchen in the morning and you see your coffee pot or your coffee machine and you automatically do the sequence of things that get you coffee, which in this case is the reward. It’s as if you’re on autopilot and you can do the same thing over and over without having to make a decision.

Milkman: One of the things we’ve talked a lot about on this show is that when we develop shortcuts or heuristics, they can lead us to make mistakes. When do you think that can be an issue with habits?

Wood: Well, that definitely happens with habit. Most of us are probably more aware of our bad habits than we are our good ones. And bad habits are simply habits that aren’t consistent with our current goals. So say I started going to the vending machine for lunch and getting donuts just because it was easy. A few times, doing that was best for me because my day was too busy and I had to eat something. But over time it’s probably not that healthy. If going to the vending machine forms into a habit—I automatically start walking toward the vending machine around lunchtime — that’s probably not very good for me.

So habits definitely go awry because we’re not continually evaluating them and deciding whether they’re what we want to do. Instead, habits are our minds’ way of simplifying repetition so that we keep doing what got us rewards in the past. And that’s not necessarily always going to be behaviors we value.

Milkman: You mentioned that most of us are more aware of our bad habits than our good ones. I imagine that’s because we want to break those bad habits. What does research tell us about how to break them?

Wood: Well, most people think that to break a bad habit they have to somehow gather enough willpower, make a strong enough decision, and form a clear intention to change their behavior. They rely on willpower to do it, but willpower is a really tough thing to rely on. Take my example about eating donuts for lunch. If you really like donuts, that’s a hard habit to break even if you know it’s not good for you. And continually denying yourself something like that just gets harder and harder over time.

What we’ve learned from research on self-control is that whatever we’re denying ourselves becomes more and more powerful over time. It’s almost like you’re controlling your temper and then finally you explode. So people’s go-to solution for changing habits is not always the most effective one. Habits don’t change easily by willpower because habits are automated and we’re not always aware of what the cues are or of the associations that are driving our behavior.

What does work to break a habit, it seems, is changing the environment we’re in, which can disrupt those cues. I could bring apples into the office so I have something ready to snack on when it gets to lunchtime and I might be thinking I should go get some donuts from the vending machine. If I have something else at the ready that will compete with my thoughts about donuts, and then I’ll be better off. A new environment will be a better way to try to shift my behavior than just exerting willpower.

Milkman: That’s great. So it seems we need to first understand how our bad habits are formed before we can determine how to break them.

Wood: Yes. Probably my favorite study on how habits are formed was one that we did in a local cinema where we showed the theater-goers a bunch of short movies and they rated how interested they were in the movies. Supposedly as compensation, we gave them boxes of popcorn. But, unbeknownst to them, some of the boxes were fresh and others had stale popcorn. Really stale popcorn. We had popped it a week earlier and kept it in plastic bags in our lab and then served it to these people. At the very end of the show we asked them how often they ate popcorn at the movies.

So we have these people watching these shorts. They got to eat popcorn and then at the end we weighed how much they ate. What we found is that people who didn’t have habits to eat popcorn at the movies did just what you’d expect: They ate more of the fresh popcorn and tended to leave the stale popcorn. That makes sense. I mean that’s rational behavior.

But people who said they almost always eat popcorn at the movies didn’t respond in a very rational way. They ate the same amount of popcorn whether it was fresh or stale. At the end of the study when we ask people how much they liked the popcorn, people who had strong habits could tell us they hated the stale popcorn just like people who had weak habits. Everyone hated it. It was awful. But people with strong habits still ate the stale popcorn and that’s the power of habit cueing. Once you’ve formed a habit, the cues are so strong that we tend to repeat the behavior even if it’s not the thing we want to do right now.

When we took this experiment out of the context of the movie theater and showed people music videos in a lab room, people who had strong habits to eat popcorn in the movie cinema didn’t act any differently than people with weak habits. It’s really the cues of the movie theatre that were making them respond irrationally. And that’s how habits are formed. We form habits by repeating behaviors in the same way in the same context, and getting a reward.

What happens is that your mind learns through repetition to associate what you did — the response you’re giving it with cues in that context. The cues could be other people, they could be the physical environment you’re in, they could even be the time of day, or some action you just did. All those cues get tied with your response in your mind.

Milkman: Let’s flip the situation now, and talk about how to form good habits. Is there anything extra we should know to set ourselves up for success?

Wood: Let me give you the example of my son. My older son is a very committed bike racer. He’s such an enthusiast that he has races every weekend. So you’d think that would be enough motivation to keep training. But even he finds that he has to organize his environment in ways that make it easy for him to keep practicing. So he puts his bike trainer in the middle of his living room. That way he actually has to move it aside in order to sit on the couch when he comes home from work. Usually it’s just easier for him to get on his bike and work out for an hour or an hour-and-a-half every night. And that’s, I think, the recipe for forming a habit that you repeat.

Making sure that you set up the situation you’re in so that the behavior is easy in that situation. And the other thing that you have to do is make sure you really like what you’re doing. So if you hate going to the gym, you’re probably not going to form a habit for it because it’s not rewarding to you. You have to find ways to add rewards which will lead to the release of dopamine in our brains that ties together the action with the pleasure that creates a habit.

Milkman: Could you explain what the difference is between a habit and a routine or even a ritual?

Wood: These are hard things to define, and the literature has not come up with a single definition, but I’ll offer you mine. Habits are specific, discrete responses that you give in a specific context and that get you rewarded. So, for example, driving is made up of a series of habits that we have all developed. We put our key in the ignition, buckle our seatbelts, put our foot on the brake to start the car…you have a whole bunch of different habits that you perform when you’re driving. You may have linked all of these together into a sequence, which is maybe better described as a routine.

And then we also have rituals. Any sports fan is well aware of rituals. Athletes have rituals, fans have rituals to try to help their team win. Rituals are behaviors we engage in that don’t have a clear reward, but that we give a sort of meaning. And the broader meaning we apply to these behaviors makes them rewarding to us.

Milkman: What are the myths about habits that you find most irritating?

Wood: Well, I do think that the 21-day thing is pretty ridiculous. From what I can tell, the idea that it takes 21 days to form a new habit comes from a self-help book, an early one in the 1960s, and it actually referred to how long it takes to get used to changes in your appearance after plastic surgery. It wasn’t even about habits and it wasn’t based on any data that we can tell and it doesn’t make logical sense. There’s no set number of days or repetitions until you form a habit, because some habits are easy to learn, right? Things like remembering to take your keys with you. You set your keys by the door, you pick them up when you leave. It’s pretty easy. Others are much more complex. Things like going to the gym, driving a car, typing on your keypad. All of those things are more complex. You can think of these behaviors as having multiple steps, first you initiate and then you actually perform it. Those kinds of complex behaviors are going to take much longer to learn and they’re going to take much longer to become a habit.

I think the other thing people misunderstand about habits is that they overlook the power of the context people were in. As I said before, many of us tend to overvalue willpower and underestimate the power of context.

There is a fascinating study done with cell phones. We all know our cell phones are being tracked in many ways, but most people aren’t aware of one study that looked at how far people carrying cell phones traveled to go to the gym. In this study, thousands of cell phones were assessed for two months during February and March. And it showed that if you travel five miles to go to your gym, you’re likely to go once a month. If you travel three and a half miles, you’re likely to go five times a month.

So the simple proximity, being closer to your gym, makes the difference between having a relatively strong gym habit and a weak habit. Most of us wouldn’t imagine that could be the case. We think we go to the gym when we’re motivated, when we have the energy, when we feel like working out. But, instead, it’s the context around us that determines how often we workout.

And whether the behavior is easy or difficult is something I think of as friction. How much friction there is on a behavior is very important to whether or not we will repeat it, and whether it will form into a habit. When there’s a lot of friction, when something is more difficult, we have to think about it hard and we might decide “Not today. It just doesn’t sound fun today.” And we won’t do it.


To learn more about habits, listen to the Creatures of Habit episode of Choiceology or pick up Wood’s book, Good Habits, Bad Habits.