Image from Wikimedia Commons
I see great suffering when people are caught up in believing that their happiness depends on external conditions. Here is an eloquent explanation of how and why this is so:
If you want to know what it means to be happy, look at a flower, a bird, a child; they are perfect images of the kingdom. For they live from moment to moment in the eternal now with no past and no future. So they are spared the guilt and anxiety that so torment human beings and they are full of the sheer joy of living, taking delight not so much in persons or things as in life itself. As long as your happiness is caused or sustained by something or someone outside of you, you are still in the land of the dead. The day you are happy for no reason whatsoever, the day you find yourself taking delight in everything and in nothing, you will know that you have found the land of unending joy called the kingdom.