one point, we all consciously decided how much to eat and what to focus on when we got to the office, how often to have a drink or when to go for a jog. Then we stopped making a choice, and the behavior became automatic.

If Eugene’s cues changed the slightest bit, his habits fell apart.

Telling someone to run their tongue across their teeth, it turned out, was likely to cause them to run their tongue across their teeth. And when they did, they were likely to feel a film. Hopkins had found a cue that was simple, had existed for ages, and was so easy to trigger that an advertisement could cause people to comply automatically.

This process—in which the brain converts a sequence of actions into an automatic routine—is known as “chunking,” and it’s at the root of how habits form.

This explains why habits are so powerful: They create neurological cravings.

Just as frequently, however, there was no tragedy that preceded people’s transformations. Rather, they changed because they were embedded in social groups that made change easier.

“That’s why signing kids up for piano lessons or sports is so important. It has nothing to do with creating a good musician or a five-year-old soccer star,” said Heatherton. “When you learn to force yourself to practice for an hour or run fifteen laps, you start building self-regulatory strength. A five-year-old who can follow the ball for ten

If you want to start running each morning, it’s essential that you choose a simple cue (like always lacing up your sneakers before breakfast or leaving your running clothes next to your bed) and a clear reward (such as a midday treat, a sense of accomplishment from recording your miles, or the endorphin rush you get from a jog). But countless

By focusing on one pattern—what is known as a “keystone habit”—Lisa had taught herself how to reprogram the other routines in her life, as well.