But misunderstanding the role of hydration, heart-rate, and sweat-rate is a mistake first-time marathoners (and other runners) often make, says Ross Markowitz, who oversees training for the renowned marathon training program at La Palestra, a high-end wellness center that bridges the gap between fitness and medicine. And increasing your understanding can get you across the finish line faster: “The ability to balance and control the system’s demand for oxygen via hydration may be the single most important factor for performance in endurance sports,” he says. (Are you as shocked as we are?) Excellent hydration know-how is especially important in New York, where locals do the bulk of their training for the ING New York City Marathon during summer months, when the heat can be crippling. (You haven’t forgotten about last week already, have you?) We asked Markowitz to help us understand how your hydration habits influence your body’s ability to propel you through a long run, so that you’ll never be tempted to skip a water station again. Check out his simple hydration success tips with Well+GoodNYC’s How Bad Hydration Habits Can Hurt Your Race Time.