It is difficult for you to set your mind because i feel you have fear of loss that the reason you are worried about it and don't concentrate on your betting. First thing only start this game where you are skillful and start it and only concentrate on it that what you are doing. It is not strange do happen to us, It is normal attitude of human being that we have no total control on our mindset, so same happen with gamblers. But we can try to do it.