Yes, so in order to be a happy, healthy, human being we have to believe...
It's not so much what we believe, although, of course the "what" is important too, but we must make the concerted effort to believe.
Against the odds, sometimes against the evidence. Against the wishes or thoughts of others, or even ourselves.
This believing is a sort of vision. Whether it's a mirage or hallucination or illusion, doesn't really matter. This vision must drive us.
And what is this vision? It has something to do with meaning and purpose and the idea that the future is better. This act of "believing" provides no certainties, or guarantees, it's simply a friend, a guide, a challenge.
We have to learn to like challenges...