Healthspan Mastery goes beyond hacks, supplements, anti-aging shortcuts, or rigid rules. It presents a grounded, science-based approach to living longer and living better by understanding how the body actually works across time. This book explores sensible biohacking rooted in biology, medicine, biotechnology, neuroscience, and cognitive science, refined through lived experience, and made accessible for real people in real lives where human capability meets the emerging edges of longevity science, without losing realism, ethics, or humility. After publishing Cortisol Clarity, Train Your Brain for a Healthier and Happier Life, Cellular Intelligence, and Ketosis + BDNF book, I received hundreds of thoughtful messages from curious readers around the world. Many shared that they finally understood stress, metabolism, mitochondria, or the mind more clearly. Yet almost all of them asked the same follow-up question: How do I apply this knowledge in daily life to stay healthy, resilient, and mentally clear as I age? Healthspan Mastery is my answer to that question. This book connects the dots between how we eat, move, sleep, think, breathe, relate, and age, not as isolated behaviors, but as a deeply integrated biological system. Across 35 carefully structured and distilled chapters, I explore how cellular, cardiometabolic, endocrine, immune, neurological, cognitive, emotional, and social processes interact to shape healthspan, the years we live with vitality, independence, and clarity. Drawing on more than four decades of work in healthcare, technology, and scientific research, I combine modern science with insights from anthropology, neurobiology, cognitive science, psychology, clinical studies, and long-term self-observation. Along the way, I examine both established mechanisms of aging and emerging theories, always distinguishing between what science strongly supports, what remains under investigation, and where curiosity must remain open. I did not write this as a prescriptive book. It does not dictate a single diet, routine, or philosophy. You do not need a medical or scientific background to read it, and you do not need to understand every molecule. What you do need is curiosity, respect for your future self, and a willingness to ask better questions about how your body adapts over time. Throughout the book, I share what helped me reverse metabolic syndrome, reduce chronic inflammation, restore insulin sensitivity, improve immune resilience, and regain mental clarity without surgery or long-term medication while also acknowledging that individual responses vary and that certainty ends. Healthspan Mastery is not a sequel. It is a synthesis. So, if you have read my earlier books, you will find the same clarity, honesty, and structure here, brought together into a more unified framework. If this is your first encounter with my work, you will find a complete, grounded guide to understanding how aging works beneath the surface and how to influence it responsibly to improve your healthspan. We cannot stop aging. But we can shape how we age. This hedartfelt book is an invitation to do so with awareness, scientific literacy, and intention so that the years ahead are lived with strength, meaning, and confidence rather than fear or decline.