Feel The Pain
When developing your applications, you need to feel the pain of your customers. While your application may benefit customers, their problems are ultimately because of your app. If you don’t feel their pain, then your application’s quality will suffer.
This idea can be applied to other areas. In design, designers need to feel not only the pain of their designs from their customers but the pain in implementing them. It is far easier to draw pictures than to implement user interfaces with code. For web application architecture, architects too need to feel the pain of their designs. While they think they’ve come up with a brilliant plan for modularity and system cohesion, it still may be difficult to implement.