Being prepared is one thing, but this quote is asking you to take it to the next level. Noah was tipped off that the flood was coming, but life doesn’t always work out that way. You almost have to assume that something bad is going to happen at some point in your future, so why wait until it occurs to try to deal with it then?
Prepare yourself for a disaster and if it doesn’t come even better. But if it does you’ll be able to handle it better and get through it more easily. It’s not a form of negative thinking to prepare for hardship, in fact it is a way of preserving your positive thinking even through rough times.