In my teens and early twenties, I had a fascination with neuroplasticity and neurogenesis. This obsession led to a book by Dr. Ernest Rossi, The Psychobiology of Gene Expression . The fundamental insight: three conditions optimize gene expression and neurogenesis—novelty (new, surprising experiences), environmental enrichment (stimulating, varied environments), and exercise (physical activity). Though this book was published in 2002, the premise behind the insights has contin