Have you ever looked at a visual puzzle where you had to relax your eyes and “let yourself” see the hidden image?  If you were able to do this, you probably noticed that you had to let it happen at first. Later you could let it happen more easily, and later still you could see the image whenever you wanted; you were in control.  Think of tai chi in this way.  First you have to let it happen.  Later you’ll learn to control it.