There's another thread about what one thing really helped your game, but the options are all tangible actions, such as reading books or taking lessons. Here's a twist: what mental concept dramatically helped your game once you "got it"? For example, my backhand improved tremendously recently when I started to think of "pulling" the racket instead of pushing it. Can you think of a time you suddenly figured something out? Maybe something you heard a million times, but it never helped you until that day on the court when a light bulb went on inside your head? Tony Robbins says the way to improve quickly is to copy not only the physiology of a successful person, but also his belief system. So what beliefs, thoughts, or ideas made you a better player?