The problem is that few people understand what happiness is nor how to get it!
As Jewish mysticism and positive psychology attests /explains, when we are thinking positively, when we believe things are good, then we are automatically happy!
It is only due to abuse that man falls into depression, then jealousy over those who have not been abused and have a positive worldview.
This is the reason for bullies, antisemitism etc. etc.
This is clearly seen that the American society which uplifts instead of denigrates (like the German society) has a nation that actually loves the Jewish people, for they are not jealous of their good lives.
Ultimately, man can either be a victim or a creator, he can react or he can act!
If life is good, then obviously we will only be seeing the good, hence be happy.
But no man is without a bump in the road!
Ah, here lies your ability to choose between life and death!, for you can control what you think about!
If you choose – make a firm resolution – to only see the good, for even the vilest act has some kind of good! (for example the Previous Rebbe relates how when the bombs fell shattering buildings, killing people and he and other Jews were huddled in a basement in Warsaw, nevertheless as there is always some good, he chose to recall how every Jew no matter how secular they seemed all cried together Shemah Yisroel attesting that all Jewish hearts are alive with love for God.)