Eckhart Tolle is considered one of the world's most influential spiritual teachers - a master of inner calm and peace. In a nutshell, he teaches that you are not your mind. In fact, Eckhart says, your mind is your worst enemy. It overtakes the real you and creates thoughts that make you miserable. So if you want to achieve peace, you've got to disassociate yourself from your mind. The key ? Live in the present.