I have one problem here, and that is the fact that you’re mixing two things: I agree with the three commitments you identify in Scrum (quality, improvement and help/team). Those are all intrinsics of something, and can be true over time. They also don’t require an unknown amount of input in order to achieve the output.
The problem I have is when you mix this with “I’m going to drop 20 pounds in four months” - that’s fixed quality, scope and time - what you have left to play with is effort/overtime. This speaks against sustainable pace.
What I’m saying is - I like the ideas, the commitments you’ve identified, but I think the analogy could be improved/replaced.