Mental fatigue

A paper published in 2009 called "Mental fatigue impairs physical performance in humans" showed that if the people do something that causes mental fatigue (computer games in this case) and then exercises, the perception of effort during physical exercise seems much higher than if there was less or no mental fatigue. Those who suffer from mental fatigue are likely to quit 15 percent earlier during training.

One of the hot training topics these days is how quickly you lose fitness when your workouts are reduced. 

But you could also lose fitness faster because of what's going on in your head.