Customers develop buying rituals, like working with a specific rep or receiving a customary discount, that provide a sense of control. When a salesperson imposes a more 'efficient' process, the customer feels the pain of losing control, a feeling twice as powerful as the pleasure of any potential gain.

While the goal is often a frictionless experience, some friction can be a positive filter. Descript found that users willing to download a desktop app were more invested and more likely to stick around. Don't be afraid of early steps that test a user's commitment.

Customers often rate a service higher if they believe significant effort was expended—a concept called the "illusion of effort." Even if a faster, automated process yields the same result, framing the delivery around the effort invested in creating the system can boost perceived quality.

Contrary to the economic theory that more choice is always better, people sometimes prefer fewer options. Removing a tempting choice, like a bowl of cashews before dinner, can lead to better outcomes by acting as a pre-commitment device, which helps overcome a lack of self-control.

Instead of reminding users what they gain from Prime, Amazon's cancellation flow quantifies the exact amount of money a user will lose by canceling. This loss framing is more powerful than gain framing because losses feel twice as painful as equivalent gains.

Netflix requires early action scenes and repeated plot points because they directly compete with viewers' phones for attention. Unlike traditional filmmakers with a captive theater audience, Netflix must optimize for retention in a distracted home environment, treating content more like science than art.

The physical friction of accessing cash in a safety deposit box creates a powerful behavioral barrier against impulsive spending. This makes it a more effective tool for building savings than a one-click transfer digital account.

Willpower is an unreliable tool for financial progress. Instead, strategically add small obstacles to curb bad habits (like impulse spending) and remove barriers for good ones (like investing). This environmental design changes behavior more effectively than self-control alone.

Shoppers are approximately twice as likely to leave a brick-and-mortar bookstore with an unexpected purchase than if they had browsed online. The sensory experience and trusted recommendations from human booksellers create an environment for genuine discovery that algorithms, focused on past behavior, cannot replicate.