“Daddy,” she said, “I want to talk with you. From the time I was three until I was five, I whined a lot. But I decided the day I turned five to stop whining. And I haven’t whined once since. . . . If I could stop whining, you can stop being such a grouch.”
Much easier said then done, but when you find the inner desire to change a behavior its much easier than trying to work against yourself.