In practical terms, the size of our energy reservoir depends on the patterns of our breathing, the foods that we eat and when we eat them, the quantity and quality of our sleep, the degree to which we get intermittent recovery during the day, and the level of our fitness. Building a rhythmic balance between physical energy expenditure and recovery insures that the level of our energy reserves remains relatively constant. Pushing past our comfort zone—and then recovering—is a means by which to expand physical capacity wherever it is insufficient to meet demand.
