A Little Fuel Is Good for a Morning Walk Your body needs fuel in order to have better stamina and get the most out of exercise, including walking. But too much food awaiting digestion can leave you feeling uncomfortable. Each person has different needs and tolerances, and it also depends on how far and how fast you'll be walking. You may not need any fuel for a 15-minute easy stroll with your dog. But you'll need some for a long, brisk exercise walk.