Lesson 11 (Abstractions move complexity) and Lesson 20 (Time > Money) are two sides of the same coin. In engineering, we talk about "leaky abstractions" in our code. But the biggest leaky abstraction is often our own health. We treat our bodies as a "boring dependency" that will always work, but burnout and RSI (Repetitive Strain Injury) are essentially the ultimate system outages. Just as "Novelty is a loan" (Lesson 5), neglecting your physical "hardware" early in your career is a high-interest loan that you end up repaying in your 40s. Real seniority isn't just about navigating people and politics—it's about managing your personal energy so you actually have the health to enjoy the "compounding" (Lesson 21) that comes at the end.