The good news is, a lot of it is imaginary/fictional, in the context of our own lives(it can't all be true at once from our own perception at least). I think the concept of "Suffering that is not necessary and is avoidable through a clear mind" is important. It's possible to go through the ordeal of missing your wallet without any or very minimal suffering, or it's possible to have a complete breakdown. I think we're very flexible creatures and can be molded towards one or the other of the two extremes.
This can be applied(with much greater difficulty) to big things, like, say, ... suppose the works of HP Lovecraft are much more reality than fiction. What is the point or the utility of fear here if this is the nature of things? All one can do is accept it, and the sooner, the better. Or one can flounder in neurosis, wish it weren't the case, pray to wake up from the nightmare, panic, scream, etc. In this case, fear is just a kind of evolutionary mis-firing that tries to pilot us towards some sort of adaptive space. It's a shit strategy if you're already in an unavoidable, horrific hellscape. And this fact can be realized with clarity or we can just be totally ignorant of it, but it's that realization that softens anxiety. Easy to say and hard to do if your eyes are bleeding because you're face to face with a Great Old One, but... the idea here isn't to use some kind of magic willpower, it's something that takes years of deliberate practice.
If you do an image search for Thich Quang Duc, a person can't do that through willpower and gritting their teeth, that's not what is going on when he doesn't scream or flinch despite burning alive. Someone like that would be best fit to survive the kind of encounter I'm describing above with minimal or even zero suffering, and it's because they trained their mind for it.