I try to repeat that at least 2 times a day:
The problem with Photoshop is that what’s being created is actually a fiction. It somewhat resembles what the final product might look like, but it’s not real. Layout and typography decisions are made that often don’t translate accurately to HTML. We spend hours designing for a medium that’s interactive and responsive, but we start by producing mockups that are static and inflexible. If great design is not only aesthetics but also how it works, then it’s time to make development part of the creative process.