From The Secret Daily Teachings
Do not worry at all about negative thoughts, and do not try to control them. All you have to do is begin to think good thoughts each day. Plant as many good thoughts as you can in each day. As you begin to think good thoughts you will attract more and more good thoughts, and eventually the good thoughts will wipe out the negative thoughts altogether.
May the joy be with you.
Amazing it is- and, it works! Believe me, I tried it and I implement it. Makes a world of difference.