I don't like these kinds of posts, because they suggest that happiness is something just within our grasp, if only we did the exact right thing to grasp it. In this case, it's suggesting happiness comes in part from questing to find major change X in your life that will change everything. But I think that's actually the cause of a lot of unhappiness. It's a perpetual "grass is always greener" situation. Say you go on…
We actually need very little to be happy, but people now live their lives in way they were not designed to be. As a primordial tribesmen, all people needed were the love and camaraderie of their fellow tribesmen (ie work with close friends), enjoy the thrill of going out on a hunt and being recognized for success (self driven accomplishment and social status), find a mate and raise a family without being a wage slave (adequate free time, no boss), and other aspects of life where you are free to choose.
Today's corporate world has none of these simple aspects. You don't get to choose your colleagues and often don't have anything in common with them. Your work is often assigned to you, and both recognition and reward is shifted towards the company or boss. You have a boss. You make money but all your time is taken away.
You might argue we are materially better off, but biologically our brains our programmed to be happy in the old tribal way.
Some of Paul Graham's essays talk about the same issues.