Hospitalized with a freak case of tropical pneumonia, goaded by his wife telling him, “I don’t want to be a widow at forty-five,” and ashamed of a middle-aged body best described as “a python that swallowed a goat,” A.J. Jacobs felt compelled to change his ways and get healthy. And he didn’t want only to lose weight, or finish a triathlon, or lower his cholesterol. His ambitions were far greater: maximal health from head to toe.

The task was epic. He consulted an army of experts— sleep consultants and sex clinicians, nutritionists and dermatologists. He subjected himself to dozens of different workouts—from Strollercize classes to Finger Fitness sessions, from bouldering with cavemen to a treadmill desk. And he took in a cartload of diets: raw foods, veganism, high protein, calorie restriction, extreme chewing, and dozens more. He bought gadgets and helmets, earphones and juicers. He poked and he pinched. He counted and he measured.

The story of his transformation is not only brilliantly entertaining, but it just may be the healthiest book ever written. It will make you laugh until your sides split and endorphins flood your bloodstream. It will alter the contours of your brain, imprinting you with better habits of hygiene and diet. It will move you emotionally and get you moving physically in surprising ways. And it will give you occasion to reflect on the body’s many mysteries and the ultimate pursuit of health: a well-lived life.