“Everybody has a plan until they get punched in the face.”
That’s it. That’s the bonk. That’s the West Nile, the sprained ankle, the Giardia. That’s the broken pack, the rain for 13 days, the missed phone bill. That’s the not showering and the not enough food. That’s losing your toothbrush or having your camera stolen.
The trick is to know that the punch is coming. You can’t plan for the specific punch, but you can know that the punches coming, and you can coach yourself ahead of time to just stop and breathe.