There is only one way to be really happy in this world, and that is to be the one that allows the things that are happening to be as they are. It takes half a second for the information to reach your brain. So what you perceive as now has already happened. It is futile to resist something that has already happened so why fret over it. Instead you should allow it to be as it is. That is not the normal human reaction. Most people make resistance to what is. Almost everything is negative and people try to flee this moment. If they are together with others they complain over politicians, the prices, other people, and so on endlessly. If they are alone, they complain internally, carrying unsatisfactoriness inside themselves. That is suffering as Buddha noted. But by accepting and allowing the present moment to be as it is, you see the world as it really is without judgment. Thus you can act intelligently. And that my friend is the end of suffering. 
P.S. How do you allow what is to be? You must watch yourself. All the time? Yes! This watching must become your second nature. Notice when you fall into complaining over what is. Do you need to do anything else beside noticing? No, noticing is enough. Noticing will automatically give the appropriate feedback and make the necessary adjustment all by itself.