A former colleague of mine moved into a new apartment with this incredible shower. It was a multiple story shaft where you could see the sky out the top. She told me, "When I moved in, I thought that shower would change my life. Now it's just my shower."
It's so easy to be caught in the loop of looking for happiness "out there." If only I get this next (job, car, house, baby, partner, bacon cheese burger), then I'll be happy. The nature of the surface layer of reality is change, so the moment you get whatever it is, there may be temporary happiness, then the goal posts move.
They say true happiness comes from within, but you can't just think your way to "within." When we meditate, what we are doing is accessing within. By doing so, we rewire our brains and reorient our minds to the unchanging place of unity which then starts to be reflected on the surface layer.
Over time, no matter what is going on–you get hired or fired, you get married or divorced, you get a cheeseburger or they're out and you have to get a salad–there is still a steady current of joy and adaptability. You don't just think that everything is one, you feel it. And then there it is, with no cause or reason–happiness.