I would disagree with the notion that someone should ‘accept’ that the worst WILL happen.
In a position like Eisenhower’s, I can see preparing a statement; he had duties on the physical plane - and nobody really ever *knows* how things will go.
But ‘accepting’ the negative, in one’s personal mind, is opening the door to it.
Within ourselves, for the best chance at the best outcome, we have to accept and expect only the Best.
‘Imagination is a great Nation’, as my old Granny always said :-)
There you are, you have thrown the dice - and events are out of your hands. At that point, all you can do is worry - and you need to control the worry. So figure out exactly what you are worrying about - what’s the worst that can happen - and live with that. Then when events turn out better than the worst case - which will almost always be the case - you are happy and able to carry on. Otherwise you look at the hole rather than the donut.