Yes, NO is the most powerful word you can ever use.
How? Let me explain.
Saying no is the best choice you will ever make. Say no to that yummy but cholestrol-rich food.
Say no to laziness. Get up in the morning for a walk.
Say no to excuses. Call the friend who you have been meaning to since a long time.
Say no to your past. Welcome the present.
Let the NO work in your favour and make your life positive.