Sri Chinmoy: What actually happens in your case is that when you enter into the physical world — playing tennis or other things — you do not give value to the physical as such. You remain in the mind. A portion of your existence you throw into the game and another portion you keep totally in the mind-world. It is like cutting yourself in half. You are keeping your body on the first floor, but your consciousness is always on the upper floor, in the mind. If you can direct more of your mental energy into the physical when you play, this will not happen.
You want to play; you want to win. But actually the concentration of the mind, the real concentration, is not in the physical itself. You know that you are playing tennis, but the concentration that the body needs from the mind is not there. There is a gap. The body without concentration from the mind is helpless. So, when you play, do not think of your mental work. Your mind may not be aware that it is thinking of the wrong thing, but it is one thing not to be aware of doing the wrong thing and another thing to concentrate consciously on the right thing. Inside you and all around you there are many beings. Because there is a gap between the mind's concentration and the physical activity, these beings can attack the physical. They need not actually be wrong forces, but they may create unfortunate experiences in life.