Is physical activity ever bad for your health?

Very much so: Remember, there is always such a thing of too much of a good thing. In fact, there is an evolving body of evidence that prolonged(over many years) vigorous exercise may be harmful ... even in regards to long-term survival! "Overexercising" more commonly acutely presents as fatigue, persistent muscle soreness, extreme sleepiness, depression, and difficulty concentrating.