The best way to be "happy" is to balance your brain chemicals, but that requires physical and nutritional discipline, which some see as 'suffering'. I don't deny myself the occasional feast, and always make sure I have enough rest, but exercise and balanced meals are a must of happiness.
As for the rest, you're confusing 'contentment' with the normal up and down of human existence in a changing environment, and 'satisfaction' with the outcomes of life: success or failure. I, for one, see as much value in failure as in any success. In fact, when I succeed (especially without challenge), I find no value in that success and move on to other things.
Religion, false beliefs, these do not bring happiness or contentment. Suppressions and supernatural beliefs are often used as a facade for 'happiness', and if you can con enough people into playing your game, you can be a 'success'. But it's all a false goal. Realizing that there are no supernatural beings, and that there is no intrinsic 'meaning' to life, the universe, and everything, gives you the liberty to either become a depressive nihilist or else create your own meaning for your life, and build the world as you would like it to be.
Become.
