With a good night's sleep you're more likely to feel fresh and alert. Regular exercise raises your overall energy level, so you may feel less need for a boost. Take a brisk walk instead of smoking if you start feeling sluggish. Moving around is a drug-free stimulant. Eat regular, nutritious meals.
Healthful foods are a great natural source of energy.
Drink lots of cold water. It will refresh you as it helps clear your body of nicotine. Avoid getting bored, which can make you feel tired. Keep your mind active, perhaps by calling a friend, reading a new magazine, or playing a game.