You either do it or not. There is no try. It's either there or it's not.
It's never off in the distance somewhere, so you can see it coming. Nobody ever says, "I don't trust you right now, but next Tuesday should be great."
Trying to trust is like trying to fly. No matter how fast you flap your arms, you're not going anywhere. And you look like an idiot.
It's one of the easiest things to lose, and one of the toughest things to get back.
Sometimes trust can be regained, but it will do so in its own sweet time. Don't bother trying to rush it, you'll only make things worse. Same thing with trying to use guilt.
It can't be reasoned into existence, either, because it's a heart thing, not a brain thing.
Oh, and everything I said about trust also counts for forgiveness.