Here, let me explain.
1. Talking to yourself means "MOTIVATE YOURSELF." Sometimes in a game we just need some motivation to push ourselves to play better. This has happened to me several times in my chess career. Recently, in April in the All Girls Championship in Chicago, I found myself in one of these situations. It was the 5th round and I was not in a favorable position but after talking to myself to remember some coaching tips and motivating myself I calmed down and won the game.
2. Talking to yourself means "LAYING OUT A PLAN." Sometimes when you talk to yourself you can straighten out your plan. It's helpful to also ask yourself questions like, "How can I better my position? Where do I attack? What square is key to my position?"
3. Talking to yourself means "CALMING DOWN." It's normal to get nervous before or during a game. We are only human! Our emotions go wild, and the best way to relax is by talking to yourself. Go over your strengths and game plan. It will help you calm those nerves and once the nerves settle down, chess begins to flow.
So remember, when you need motivation, when you need to clear your plan, or need something to calm you down - talk to yourself! After all, the worst enemy on the board is not always your opponent but ourselves. I hope these tips that I practice continually will help you out.
Here are two of the best games played against me in my last live chess session (remember I play most Friday nights, along with other masters, from 6:30-8:30 Eastern).
In this one, my opponent almost finds a cool back-rank checkmate, but I sacrifice my queen back and win in the king-and-pawn endgame!