I know how you feal with it. Someone else gave those advices :
Strategies (which work for me – and are hopefully portable):
1. Talk about it (or, in my case, type it the comments) as if you were having a conversation. Record that conversation. Either by using a recording device, or by typing as you speak, or by having someone else write or type up your words as you speak them.
2. Take a lot of caffeine – it DOES work a little bit like ADD/ADHD meds do in lowering the ‘barriers’. Avoid sugar/sweeteners – they minimize the function of the caffeine. (Yes, this is self-medicating….but, at least, caffeine is not a narcotic or anything…)
3. Put the ‘words you spoke’ into a word-processing file, version 1
4. Re-organize the sections into the proper order for whatever format you require them to be in.
5. Edit the words to form paragraphs in the proper format.
I dont know if it helps