When designers intentionally trick users into inviting friends or blasting a message to their social networks, they may see some initial growth, but it comes at the expense of users' goodwill and trust. When people discover they've been duped, they vent their frustration and stop using the product.

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

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.

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

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

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.

Instead of relying on expensive marketing, habit-forming companies link their services to the users' daily routines and emotions.