You can set rules for the best case scenario or you can set rules for the worst case scenario.

When you use the best case scenario as a basis, you trust that things will progress well, that people are trustworthy, that nothing terrible or horrible will happen, that “bad” is a situation that can still be managed without much pain.

When you use the worst case scenario as a basis, you look at what will go wrong, at those who will betray you or not keep their part of the deal, at principles that need to be protected, at a “good” situation that is very difficult to digest.