From an observational point of view, everything in nature comes in pairs. Any adjective has its opposite. Bright/Dark, White/Black, Happiness/Misery, even conceptually god can't exist without the devil. Having said that, if things are measured that way, then the universe is balanced. The more happiness there is, the more unhappiness will exist somewhere else...Like it or not.
What we are offered, I think, is freedom of choice, to choose between happiness and Misery.
I think generally people don't wish to be only happy. They relate happiness to worldly pleasures and desires. But desire can't be satisfied, the more you eat, the next day you want more and more, you get a Honda you want Mercedes, you get Mercedes you want the latest, you marry the most beautiful you still desire another...Desires differ from person to person but they are all unattainable in the long run.
Happiness becomes last on your wish list. Another reason for not putting it first, is because you may be granted happiness but on the expense of other items, the beautiful car, the promotion you always wanted at work..Etc. I think even consciously if people are offered to be more happy or offered another materialistic wish, they will choose the latter. Happiness can come later. So, it gets pushed and pushed till the last day of your life..
So to change that, you need to place your Joy and Happiness above all. Don't concern yourself with the miseries of others for now. Take care of yourself first then turn to defend other's miseries because if you don't, you will be sucked into their miserable hole.
The universe doesn't care about your choice, or in fact it will honor it either way. If the whole earth decides to be miserable, it will be perfectly fine and happiness will be found on some other planet...