To be happy you must be content.
To be content you must be grateful.
But how can you be grateful?
Take a piece of paper and fold it in half length-wise.
On the left side write down everything in your life. Everything. Every relation, every friend, every sock, even the expire yogurt in the back of your fridge including the fridge itself. This may be somewhat time consuming and quite lengthy but don't forget to include your parents, your siblings, your children, your pets and your aunt with the uni-brow.
Now, on the right-side write down everything the universe OWES you.
When you suddenly realize how much you have and compare it to the fact the universe actually owes you nothing whatsoever you will be grateful for what you do have and that will make you content and that contentment will make you happy.