Positive people are physically healthier: They have lower blood pressure, a lower heart rate, lower levels of stress-related hormones, and a good immune system. 

Positivity reduces stroke and diabetes. 

People who experience more positive emotions sleep better and are less anxious. Basically: Changing your attitude from a negative to a positive situation leads to a better life and better success. When you feel good, you are more productive and, if you are more productive you can reach your goal faster.