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.

For an infrequent action to become a habit, the user must perceive a high degree of utility, either from gaining pleasure or avoiding pain.

Fogg states that all humans are motivated to seek pleasure and avoid pain; to seek hope and avoid fear; and finally, to seek social acceptance and avoid rejection

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.

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.

Brainstorm new interfaces that could introduce opportunities or threats to your business.