When you’re sick as a dog, nothing sounds worse than the gym (shudder). But should you push yourself to sweat it out, or tuck up in bed and sleep your way back to life? It depends how sick you are, says Bobby Morrow, spokesman for American Council on Exercise. If you’re sniffling like a sick puppy, sure, do some light cardio to keep your immune system up (disinfecting your machine better than ever when you’re done, of course). But if you’re achy/feverish with more of a flu? Bed rest for you—your body needs time to heal. Besides, let’s be honest: No one wants next-dibs on a Stairmaster with a side of Swine.