A riverbank looks solid until the spring melt. Know what your ground is made of before the high water comes.

Plenty of arrangements hold perfectly well until they are tested, and then you learn what they were actually built from. The friendship that works when nothing is at stake, the plan with no second option, the money situation that assumes nothing breaks: all of them look like solid ground in a dry season. The test arrives eventually and does not ask whether you are ready.

Pick one part of your life and ask what happens if the obvious thing goes wrong: the phone dies, the ride falls through, the shift gets cut. Build the cheap backup now. One spare, one alternative, one person you could call.