Both ancient philosophy and modern psychology suggest that darker thoughts can make us happier, writes Oliver Burkeman.
Positive affirmations works great in an environment where we feel comfortable already.
Evaluate the worse case scenario by using "negative thinking" and explore opportunities then solutions will often provide better results under stress. Indeed as explained in this interesting article, by anticipating this worst case scenario the power of anxiety and stress from the situation lessens.
See on online.wsj.com