What makes a Startup "Lean"?

I recently revisited 'The Lean Startup' and was blown away by how much more I got out of it the second time around. I'm gonna simplify it into what I call the 'Five Core Principles of Building Startups The Lean Way 🐆.' Here's a breakdown of what I learned: 1. Build, Measure, Learn: This means constantly testing your ideas, gathering real data, and using that feedback to improve your product. 2. Validated Learning: Instead of guessing, focus on learning what your customers really want by testing and validating your assumptions. 3. Minimum Viable Product (MVP): Rather than perfecting your product before launch, create a version with the minimum features needed to satisfy early customers. 4. Pivot or Persevere: It's important to be flexible and willing to change direction if your initial approach isn't working, but also to know when to stick with your vision. 5. Innovation Accounting: This involves tracking the right metrics to measure progress, which may not always be traditional revenue metrics. Have you applied any of these concepts to your startup? What else have you guys learnt from your experiences?