The document discusses how to plan for career changes by having flexible plans that account for different scenarios. It recommends crafting a primary Plan A, an alternative Plan B, and a fallback Plan Z. Plan A is one's best strategy given current knowledge, Plan B is an alternative if goals or methods need to change, and Plan Z is a reliable backup plan to regroup if things go seriously wrong. The document provides examples of what Plans A, B and Z may look like for different career stages such as launching a new career, moving up in an existing career, or shifting to a new career field. It concludes that having Plans A, B and Z will help one adapt to changing circumstances no matter where they are in their career