I do not think it is possible to be happy forever.
I think I can explain most of this when I think of the ocean. Everything is part of an ocean. Nothing stays in the same place.
Every living (and even dreaming) moment is like a wave. Transient, perpetually moving and changing.
As optimistic as I may be (I identify as an optimist bordering on idealist), I am also realistic enough to know that I am not going to be happy no matter what from point x and forward. There are going to be moments and days when people and things are going to disappoint, sadden and anger me; there are going to be experiences that will leave me terrified or heartbroken.
It’s not so much about hoping to stay happy from a certain moment forward—it’s more about being able to stay resilient, just like a wave. There’s the crest of a wave and the trough of a wave—the ups and the downs.
It’s about being able to get back up after being knocked flat by a crushing wave. It’s about resisting the pull of a tide, clawing your way back to the shore after being ripped and tossed out to sea, it’s about finding air and being able to breathe again after being plunged an immeasurable distance underwater.
We are capable of doing all of these things.
The objective (or mine, at least) is not to stay happy but to ultimately be happy.