I read somewhere that there are 2 reasons for unhappiness in life : (1) You are not getting what you want (2) You got or are getting what you want.
So - what does this mean? It looks like a paradox. The message is simply trying to imply that unhappiness is in our minds. Unhappiness is not due to the external circumstances but our internal thinking. The process of life, the process, and the actions of trying to achieve something are in themselves fulfilling. Desires are endless. The moment you achieve something, the next thing will pop up in your mind for the next achievement.
You study and pass your college exams. That is an achievement but then you want more, you want a job. You get a nice job but then you want more, you want promotions or a higher salary or such. You want a perfect relationship. You buy a house, a car, nice amenities, etc but we always want the next thing!
How to become happier? Well, let go of the outcome and accept and embrace life totally believe in the power that is running the entire universe and it is also running within you!