This process within our brains is a three-step loop. First, there is a cue, a trigger that tells your brain to go into automatic mode and which habit to use. Then there is the routine, which can be physical or mental or emotional. Finally, there is a reward, which helps your brain figure out if this particular loop is worth remembering for the future.

This explains why habits are so powerful: They create neurological cravings. Most of the time, these cravings emerge so gradually that we're not really aware they exist, so we're often blind to their influence. But as we associate cues with certain rewards, a subconscious craving emerges in our brains that starts the habit loop spinning.

This is how new habits are created: by putting together a cue, a routine, and a reward, and then cultivating a craving that drives the loop. Anyone can use this basic formula to create habits of her or his own. Want to exercise more? Choose a cue, such as going to the gym as soon as you wake up, and a reward, such as a smoothie after each workout. Then think about that smoothie, or about the endorphin rush you'll feel. Allow yourself to anticipate the reward. Eventually, that craving will make it easier to push through the gym doors every day. Cravings are what drive habits. And figuring out how to spark a craving makes creating a new habit easier. To change a habit, you must keep the old cue, and deliver the old reward, but insert a new routine. That's the rule: If you use the same cue, and provide the same reward, you can shift the routine and change the habit. Almost any behavior can be transformed if the cue and reward stay the same.

THE GOLDEN RULE OF HABIT CHANGE: You Can't Extinguish a Bad Habit, You Can Only Change It.

HOW IT WORKS: USE THE SAME CUE. PROVIDE THE SAME REWARD. CHANGE THE ROUTINE.

Belief is the ingredient that makes a reworked habit loop into a permanent behavior.

We do know that for habits to permanently change, people must believe that change is feasible. The same process that makes AA so effective--the power of a group to teach individuals how to believe--happens whenever people come together to help one another change. Belief is easier when it occurs within a community.

If you focus on changing or cultivating keystone habits, you can cause widespread shifts. However, identifying keystone habits is tricky. To find them, you have to know where to look. Detecting keystone habits means searching out certain characteristics. Keystone habits offer what is known within academic literature as "small wins." They help other habits to flourish by creating new structures, and they establish cultures where change becomes contagious. Keystone habits transform us by creating cultures that make clear the values that, in the heat of a difficult decision or a moment of uncertainty, we might otherwise forget.

This is how willpower becomes a habit: by choosing a certain behavior ahead of time, and then following that routine when an inflection point arrives.

A Reader's Guide to Using These Ideas

THE FRAMEWORK:

• Identify the routine

• Experiment with rewards

• Isolate the cue. Almost all habitual cues fit into one of five categories: Location; Time; Emotional state; Other people; Immediately preceding action

• Have a plan. Once you've figured out your habit loop--you've identified the reward driving your behavior, the cue triggering it, and the routine itself--you can begin to shift the behavior. You can change to a better routine by planning for the cue and choosing a behavior that delivers the reward you are craving. What you need is a plan.