You'll often find that people's declared preferences - what they say they want - are far different from their revealed preferences - what they actually do.

Users who continually find value in a product are more likely to tell their friends about it.

Why not live now instead of someday?

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

As fleeting commitments, diets often fail. Thinking of dietary choices as part of who you are...can give them real staying power

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