1.A big meal full of carbohydrates and fats can tire you out.Eat small low fat meals four five times a day. 2.A large bowl of curds and fruits after lunch gives you a fullness and well being. 3.Take few deep breathes.It leaves you refreshed. 4.For quick revive get up and move around or go for a brief walk. 5.Inhaling some essential oils can give you and instant lift.