Aging, despite its dismal reputation, is actually one of the great mysteries of the universe. Why don't we just reproduce, then exit fast, like salmon? Could aging just be one big evolutionary accident? Is senescence, the gradual falling apart of our bodies, at least partially avoidable? Can we extend the healthy lifespan and reduce the lingering, debilitating effects of senescence?

Aging -- Run for your life -- Sitting kills -- Heart of the matter -- Energy-converting machine -- Bigger, better, stronger -- Boning up -- Exercise and cognition -- Exercise and mood -- It takes guts: exercise and the microbiome -- Immunity, inflammation and exercise -- Exercise and cancer -- Those tiny, telltale telomeres -- Exercise and anti-aging pills -- Nitty gritty -- Q & A -- Dodging bullets