Is it just me, or does the English sentence sound weird? I've heard people say "prepare for the worst", but never this. Does it have the same meaning?
People might not say it in those exact words often, but it's perfectly fine English.
It's just that when you read something strange like that, you wonder if the Portuguese might actually mean the more reasonable, closely related Engligh sentence that comes to mind. In lots of cases, that's what it turns out to be.
Not sure what you mean, KmRmn. "You need to consider the worst" is a perfectly reasonable translation that doesn't sound strange to me at all.
Possibly the person you talk to.
For general sense, you can use "é necessário..."