In late August 2024, the physician and longevity guru Peter Attia posted a new reel for his 1.3 million Instagram followers, featuring a close-up of a stack of golden boxes, each about the size of a hardcover book, piled up on a marble countertop. The image stood out; Mr. Attia’s grid consists mostly of snippets from his popular podcast, The Drive, and straight-to-camera clips of him sharing advice on topics like zone 2 cardio training or the importance of getting regular colonoscopies.