The habit loop

Duhigg explains that habits form because the brain is always looking for ways to save effort. Researchers at MIT found that the basal ganglia, deep in the brain, take over routines we repeat, freeing the rest of the mind.

Every habit runs through a three-step loop. A cue tells the brain to go into automatic mode, a routine follows, and a reward helps the brain decide whether the loop is worth remembering. With repetition it becomes automatic.

He tells the story of Eugene Pauly, who lost his memory after a brain infection yet could still learn new habits, such as walking a route around his block.