Aunt Barbara's Powerful Little Book of Comfort
From Chapter Five: The Power of Thoughts.
At this point it is helpful to talk about thoughts. Whatever-you-think is how things will be. Are you listening? If you think that you can't go on, you can NOT go on. If you think you will be all right, you will be all right... If you think you are not strong, you are not strong. ...Positive thoughts can turn everything around in a nanosecond.