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…
And yet there is a duality that has always struck me as important, though hard to explain: it's easiest to be happy when you're striving toward a goal you believe in. But you need to keep your sense of self, your ego, non-attached to the outcome of the striving.
That is, you need to invest yourself 100% into doing things that are important to you, but remain detached from whether you ultimately achieve what you wanted to achieve.
I think Buddhists call this "skillful attachment".