The workout: A predawn yoga or Pilates class.
For these types of low-intensity activities, a snack isn't necessary (unless you wake up famished), but hydration is. "Most people think, 'I won't be sweating much, so I don't need to drink anything,'" says Rosenbloom. But dehydration can make the workout feel much harder than it really is. A 60- to 90-minute class is a long time to go without water.