"Know thy users."
“Socrates said, “Know thyself.” I say, “Know thy users.” And guess what? They don’t think like you do.”
— Joshua Brewer
It can be easy to get caught up in design details and think that you've nailed the colors and the look, only to realize that some of the very things you love about the design are actually making it harder for the person who will use it. We're on the inside. These are our businesses so we think of them from the inside out, but the people who buy from us and shop in our stores, eat in our restaurants, use our apps—those people experience our businesses from the outside in. They fundamentally do not think about what we do the same way we think about it. They couldn't.
We have to think about them and what they want, care about and how they use what we offer. If we don't figure that out we'll fail them in our offering, and lose them.