After I learned how brain needs new stimulus, I got curious. So as usual, I went looking for a book about brain. I picked Your Brain: The Missing Manual because it seemed comprehensive enough but not too technical that an ordinary person like me could enjoy reading. And it turned out to be a very interesting and entertaining book.
The book covers a wide range of topics related to brain, from the basic mechanisms to how perception or reasoning work and how brain develops. But the parts that interested me was how brain functions to reward and motivate us.
We feel pleasure when a part of brain called nucleus accumbens give electric stimulate. And the stimulate is issued when we achieve something that your brain considers as beneficial to your biological interests (i.e. being well fed, avoiding danger, procreating, etc.). But this stimulus is temporary - it dies off quickly. Moreover, the brain gets accustomed to new sources of pleasure, so you won't get the same level of pleasure effect for the second or third time. It makes sense if you think about, say, eating a piece of cake; the pleasure dies off once you finish eating it, and the second serving won't necessarily give you the same pleasure. The brain functions this way in order to keep motivating you to do what's needed for your biological needs.
So from the biological point of view, you cannot get happiness - more of a long term state of contentment and optimism - by working to stimulate your nucleus accumbens, which only give a you temporary pleasure. This is why materialistic pursuant doesn't make you happy. This isn't just an old saying; it's scientific.
So what could make you happy? What your brain wants is the state of relaxed indifference; we need to first realize that the definition of happiness is a zen-like state of mind that's homeostasis. We also need to understand that unhappiness is what makes world go around because it fuels motivation. So focusing on experience rather than end results is the key to feel happiness.
A lot of self-help books or individuals who made significant achievement say that it's the progress, not the perfection that's important, or it's how we get there that's more important. It's very interesting and also assuring that this type of notions is proven scientifically.
So we are all doing it right by treasuring the experience rather than the result. You can still pursue short-lived pleasures by putting yourself through disciplined self-deprivation (i.e. eat only a little bit of great food, engage in pleasurable activity only so often, etc.) or through continuously switching types of pleasure sources, but just don't expect that to make you happy.