It is a kind of happiness that is truly satisfying, strengthened by noble purpose. No sensual pleasure can be equal to it. Mindfulness can also be the deciding factor between life and death. A lot of careless mistakes and oversights end in death. It may be just a slip on the stairs, a ladder, or along the road.
Traffic accidents claim lives daily.
Then there are electrical short circuits, or even choking through unmindful eating. It not only means your life, but also others. If you are mindful at the moment of death, it can mean a happy rebirth. If not it can mean hell. Mindfulness means meritorious kamma and defilements mean unwholesome kamma.