Most of the food we consume is destined for processing in the part of the cell called mitochondria to generate energy. Hence, the simple view of mitochondria has been to see them as cellular furnaces, important but rather mundane organelles. More recently they have been recognized to be hubs of metabolic activity that play a substantial role in the aging process and a wide range of human diseases. We have elucidated the molecular mechanisms underlying many of these diseases, and lately this has led to the discovery that major mitochondrial remodeling occurs in response to changes in nutrient availability. I will discuss the importance of mitochondria to all eukaryotic forms of life and its critical contributions to the health and longevity of every one of us.