If you feel tired and exhausted at the end of the day, exercise is probably the last thing on your mind. But yoga asanas, as well as breathing, relaxation, and meditation techniques, actually relieve fatigue, stiffness, tension, and stress. So take your pick, or do some of each. If you practice regularly, you'll have more energy and you'll tire less easily. But if you do get tired, stressed, and tense, you'll have some powerful tools to help you feel better instantly.