what is a healthy way to deal with uncertainty?

[Angrboda]

I think... (questionable premise) that you will worry whether things turn out alright or not. And them turning out alright (or not) will not stop the worry. It's not the things causing the worry.

I'd suggest it's expectations and habit (of worry), but I'm not up to a substantive response here right now. If Zen works for you, work it. I have derived great comfort over the years from, "Chop wood, carry water." But use your head. There's a Buddhist parable wherein a man sees another on horseback thundering by. He asks the man, "Where are you going?" And the man on the horse replies, "I don't know. Ask the horse!" The point of the parable is that an out of control mind goes where it wills; only by bringing the mind under control will you be able to get it to go where you want to go. But I think there is a second level to this parable that is unacknowledged. That second level is that pursuing answers like Buddhism and meditation can itself become a horse which goes where it pleases, rather than worrying about where you want it to take you. Meditational practice, and the flurry of metaphysical and psychological baggage which often goes with it, can deprive you of control just as surely as its opposite.

Anyway. Just spitballing here...