Here's what you need to do. Sit in a dark room, in a chair, straight up, not slouching. Get some water, a glass or a bottle of water. And just sit. For an hour or so, just sit. Drink all the water, and sit and try to clear your mind of all thoughts. Try to think about nothingness. And if you feel that it's not working, KEEP DOING IT. Tell yourself you're going to do it for an hour and then DO IT. Don't let your mind start wandering to thoughts, think about nothing. For a whole hour. And drink all the water you got for yourself. And the more you BELIEVE that it will work when you start doing it, the better it will work.
I'm absolutely serious. Do it.