But when your aches and pains extend to your chest, abdomen or, well, lower...then it's a good idea to skip the workout. Raising your body temperature when you have a fever can be dangerous, so wait until a fever that's higher than 100 degrees subsides before resuming exercise. Your body is working out on the inside in order to heal itself - don't push it to work harder. If you do decide to work out, then take care of your body, even more so than usual. Drink more water than you normally do, and pay close attention to how you feel during your workout. Stop if you feel lightheaded or dizzy. Get plenty of sleep that night, and when it's time for your next workout, reassess your symptoms and see if you feel up to it. Most important, listen to your body. If it needs a break, then oblige for as long as you need to.