Brain Myth #1: You only use 10 percent of your brain.

Fact: Over a 24 hour period, you use your entire brain. Some parts are resting, while others are active, but if neurons are not activated, they die off. Usually this happens in childhood. Did you know we are born with 200 billion neurons, but adults only have half? Where did the other half go? They were “pared off” in childhood: the useless beliefs and perceptions stored in certain neurons are replaced by neural networks that have value and meaning in our lives.

Source : http://www.praxisnow.com/brain-training/brain-myths