"Writing is easy; all you do is sit staring at a blank sheet of paper until the drops of blood form on your forehead." - Gene Fowler.
Sometimes I just have to close my eyes and a speech pops beautifully into my brain. The words come effortlessly. Sentences flow like a gentle stream of running water. They are my words and my voice but it's almost as if the speech already exists in its own right without me having to "create" it.
But those times are oh so rare!
If I'm struggling to find the words for an upcoming speech or presentation, I have several methods I use to get over the horrors of staring at a blank page for hours. One of them is to borrow Rudyard Kipling's method - he had what he called six "serving men", which were the questions:
I scribble down the answers to these questions, longhand, not necessarily to use all the answers in my speech - more to get the thoughts and words coming. Once the thoughts and words start coming, they more often lead to others, and then you're away.