This isn't flashy or going to make you swoon (unless you're a real UX nerd), but going thru the discovery phase and gaining alignment with your client is pretty satisfying. When you know that you're in sync with the vision the fun, engaging, delightful product is close at hand. I wrapped up this brief on a 0->1 client project just recently, and we nailed the scope, features, vibe, goals, messaging, and user interactions they expect to see.