This paper addresses several issues discovered by working with different industries attempting to sustain their business enterprise and to become “Lean.” The three key points addressed by the paper are: 1) Designing a new system or re-designing an existing system should focus on collecting a complete set of customer needs and deriving functional requirements from those needs. 2) Illustrating the path-dependency or sequence of implementation of Physical Solutions (PSs) to achieve Functional Requirements (FRs) of partially coupled designs. 3) Lean is not what we implement as a system, rather lean is what we become as a result of meeting customer needs with the utilization of the least amount of resources possible in a sustained manner. When lean is viewed as a set of tools to implement, the people in an enterprise will face ever-increasing diffculty in long-term business sustainability. The primary problems arise early in the design/re-design phase due to the lack of a clear set of system functional requirements. Without clearly defined system FRs, driven by recognizing customer needs/concerns, an enterprise will implement point solutions in an attempt to improve part(s) of a system. The Manufacturing System Design Decomposition (MSDD), a product of Axiomatic Design (AD), illustrates the path-dependency among the solutions of the associated requirements of any manufacturing facility. The MSDD provides a system-wide view and a clear sequence for system design implementation. The Collective System Design approach is discussed to provide the steps for senior leadership to re-design an existing system or to design a new system that results in long-term sustainability and become “lean.”