The aim is to influence customers to use your product on their own, again and again without relying on overt calls to action such as ads or promotions.

Reducing the thinking required to take the next action increases the likelihood of the desired behavior occurring unconsciously.

Like flossing, frequent engagement with a product, especially over a short period of time, increases the likelihood of forming new routines.

If users are not doing what the designer intended (when users are investing time, effort, etc in your product), the designer may be asking them to do too much.

Companies leverage two basic pulleys of human behavior to increase the likelihood of an action occuring: the ease of performing an action and the psychological motivation to do it.

To initiate (user) action, doing must be easier than thinking.

User habits are a competitive advantage. Products that change customer routines are less susceptible to attacks from other companies.