My wife and I were having this conversation about why people get upset when they learn they are going to die and it does not make sense to me that when we know we have two three months to live we waste our time being upset about it. I have three months to live and instead of going and living it and enjoying the life I have, I will instead spend it by living in the future when I dont have this life when I will be dead. That future is going to come anyway, so why dont I wait till I die to die.
If you think about how much we crib and complain about uncertainty and then you are told you are going to die. There is certainty finally we know something for sure, you would think we would be happy and yet we choose to be unhappy. So may be we are not unhappy about uncertainty or unhappy about dieing. We are just unhappy. We are in a habit of being unhappy.
I think unhappiness is a habit people learn from childhood. We learn to complain, criticize, judge. So to be happy all you have to do is to consciously choose it. Make it a habit.