Positive thinking will let you do everything better than negative thinking will. - Zig Ziglar
You’re Afraid of Negative Thinking – And It Makes You Weak! http://www.theemotionmachine.com/youre-afraid-of-negative-thinking-and-it-makes-you-weak
Declutter Your Mind: How to Stop Worrying, Relieve Anxiety, and Eliminate Negative Thinking (Mindfulness Books Series Book 1)
13 Common Cognitive Distortions - Allowing negative thinking to dominate, rather than being rational, balanced & purposeful
Negative thinking can harm our health. Learn how to take control of your thoughts and gain your health back.
Deborah's Little Gems: Can We Overcome Negative Thinking?
William Peynsaert's answer to How do I get rid of negative thinking? - Quora
Negative thinking | http://www.ilanelanzen.com/personaldevelopment/2-tips-on-how-to-avoid-negative-thinking/
Scientific proof that negative beliefs harm your health http://www.mindbodygreen.com/0-9690/scientific-proof-that-negative-beliefs-harm-your-health.html
Beware the Negative Power of Positive Thinking / smallbiztrends.com