I have the same problem as the person you're responding to, and writing is not a form of thinking (for me, at least) - generating anything to put onto the page feels like an insurmountable task. I like the GP's suggestion of making a speech, I'm likewise much better at vocalizing than writing.
I'm pretty sure there is some underlying difference and it would be good to know what it is - I was diagnosed with dyslexia when I was 14, which never really felt like a satisfying answer, though I do have some dyslexic-ish symptoms (I tend to spell phonetically when I'm very tired and often type word-correct anagrams - like "never really left like a satisfying answer", above).
I'm pretty sure there is some underlying difference and it would be good to know what it is - I was diagnosed with dyslexia when I was 14, which never really felt like a satisfying answer, though I do have some dyslexic-ish symptoms (I tend to spell phonetically when I'm very tired and often type word-correct anagrams - like "never really left like a satisfying answer", above).