I usually do distraction, or I use my mind to think in the now. I try not to project, (think negitive of), the future, or look back (think negitive of the past), with regret. There are many self help books on the market for quieting the mind and slowing down thoughts as well as being positive.

Have you ever read "The Power of Positive Thinking" by Napolian Hill or, The Power of NOW by Eckhardt Tolle?
Both are powerful books.

Good luck,