Cold plunges. Exogenous ketones. Pu-erh tea--but hold the breakfast: it's all par for the morning routine, at least if you're entrepreneur, self-experimenter, and king of the lifehacks, Tim Ferriss. From how he manages the challenges of his celebrity to how he manages to stay in great shape; how he does--and when he doesn't--harness the power of AI; and how he preps for a podcast designed to…