LET GO OF EXPECTATIONS:
Negativity often begins with expectations of yourself or others. Letting go of unrealistic or negative expectations will not only help you change your attitude, but will also create a positive environment.
Accept that nothing is perfect. Imperfection adds character and letting go of any expectations of perfection will help you focus on the positive in any person or situation.
Whenever something bad happens, forget it as much as possible and then actively imagine things you want to happen. Likewise, if a person says something negative, consider it briefly and then let it go. Dwelling on negativity will only make you feel negative.