If you realized how powerful your thoughts are, you would never think a negative thought. They can be a powerful influence for good when they're on the positive side, and they can and do make you physically ill when they're on the negative side. I don't eat junk foods and I don't think junk thoughts! Let me tell you, junk thoughts can destroy you even more quickly than junk food. Junk thoughts are something to be wary of.
Peace Pilgrim (1992). “Peace Pilgrim: Her Life and Work in Her Own Words”, p.15, Friends of Peace PIlgrim