William James (1842-1910, American philosopher and psychologist) once said that the greatest weapon against stress is our ability to choose one thought over another.
When dark thoughts or worries crowd in, say to yourself that you will decide to think differently. It seems to work somehow. I guess it is a spin on thinking positive or the idea that thoughts become things which have the ability to either eat us alive or prop us up to face another day.
I like to call it Courage.