For an athlete, each passing year is one step closer to their professional irrelevance. They say the worst thing you can give an athlete is a birthday card. In our corporate careers, we assume our paths are quite the opposite. In fact, we're told (directly or indirectly) that each year of experience is another notch on the belt, boasting time in chair as a natural rise in our level of expertise, compensation, and reputation. But if that's the case, why then do so many seemingly talented, but more importantly, TENURED people struggle to sustain success or feel professional contentment? Science tells us that athletes and artists aren't the only professions that should fear birthdays. In today’s episode, we’re exploring the psychological and management concepts: Fluid Intelligence, Crystalized Intelligence, and the Peter Principle. In understanding each, we can manage better the often unpredictable lifecycle of our careers, especially during those peak performance and earning years, when we are both the most valuable but frighteningly the most disposable.