The "use it or lose it" mental model is gaining attention as AI becomes more integrated into our lives and workplaces. Charlie Munger's insights highlight that skills, whether in music or exercise, atrophy without regular practice. For managers, this is especially relevant as they often worry about losing technical skills like coding when they transition into leadership roles. Many try to stay engaged with programming tasks through pair programming or code reviews, but the day-to-day demands can make it challenging. As AI tools take over strategic thinking and planning, there's a significant risk that critical cognitive skills could decline as well, making it essential for managers to remain actively involved in their work. Research supports the idea of cognitive decay when skills aren't practiced. Studies indicate that reliance on technology, like Google for memory or GPS for navigation, can weaken memory and cognitive abilities. A 2025 study showed that students using ChatGPT for efficiency had weaker neural connectivity and cognitive depth than their peers who didn't. This highlights the danger of offloading too much to AI, which could lead to a decline in essential managerial skills. The author emphasizes the need for managers to engage with their teams actively and avoid becoming passive observers, as neglecting critical thinking will only hasten their obsolescence in a rapidly evolving work environment. Using inversion to explore the worst practices can be revealing. For instance, a manager who distances themselves from project details, ignores new AI developments, or fails to engage in critical thinking is essentially choosing to become irrelevant. This detachment not only impacts their effectiveness but also means they're avoiding the cognitive challenges that keep their skills sharp. Munger's model serves as a reminder that continuous engagement and practice are vital for maintaining both technical and managerial competencies in an AI-driven landscape.