As the previous writer said, "Knowing yourself" is the ultimate thing one should strive for. Happiness is something you can't achieve by striving. It's a by-product resulting from doing something which 'brings' it into your life. For example, doing something you love doing, - particularly if it also makes other people happy.
The famous psychologist, Abraham Maslow went into this very deeply. He found that when the basic needs are met, we move up towards other needs. When these are met, we move up again, and again. The second highest need is 'Self Actualization,' (Wanting to be the best we can be in as many areas as we can) but surmounting even this is the need for Self Realization. Which means, of course, Knowing yourself.