The problem is with everyones perspective of happiness which is why we would all define what makes us happy differently but for the most part we're not happy, we do things that provide temporary happiness but never feel happy consistently.

Happiness is hard to achieve because for the most part we've been led to believe that we can have and do what we want in life and be happy but this just isn't the case, e.g for a career most people dont end up doing something they love but have to do something they dont just to survive, this is an unfortunate reality but because we've all been programmed to think we should all be able to do something we love and make money from it we're even more depressed when we cant.