Throwing Up
Credit: Getty Images

It should be pretty obvious that throwing up after or during exercise is not a desirable result. "I'm not saying that if you push yourself so hard you throw up, you've done damage," says Kaeding, "but I always think that's a pretty good sign you may want to reassess how hard you're pushing yourself." Getting nauseous or light-headed from your workout can indicate that you're dehydrated or experiencing heat exhaustion. Heat exhaustion can be treated with rest in a cool place but, if ignored, it can lead to heat stroke, which can cause brain damage, organ damage, and death.