Instead of thinking of a product as a series of features to be built, Lean UX looks at a product as a set of hypotheses to be validated. In other words, we don’t assume that we know what the user wants. We do customer interviews and research in order to develop a hypothesis about what a customer might want, and then we test that hypothesis in various ways to see if we were right. And we keep doing that every time we make a change to the product.
Shipping features isn't success. Making customers happy is success.