Having just finished my 10th day, I can say that a little light exercise is not only okay, but beneficial. Especially since your body is used to it. You want to keep your blood pumping and your juices moving, so to speak. Just be sure not to push yourself too far and drink LOTS of water in addition to the fast. Stretch more than usual. Also, keep track of how much carb you're getting from the maple syrup versus how much you're spending through exercise. In other words, keep it light. Have fun!