Whether you're heading off to spin class, boot camp, or any other exercise, it's always important to hydrate so you can stay energized and have your best workout. Electrolyte-loaded athletic drinks, though, can be a source of unnecessary calories, so "drinking water is usually fine until you're exercising for more than one hour," says Newgent. At that point, feel free to go for regular Gatorade-type drinks (and their calories), which can give you a beneficial replenishment boost. But worry not if you like a little flavor during your fitness: There are now lower- cal sports drinks available, adds Newgent, so look out for 'em in your grocery aisles.