You can do anything you set your mind to. You can only get used to an activity you do consistently if not, the brain and body will not adapt to the changes.
You wouldn't have been able to write a post of three hours in an hour if you didn't make up your mind and work towards it.
Writing daily isn't easy at all (speaking from experience 😂). There are times your brain will refuse to cooperate and that's because it has been stressed too much, so the best thing is just to chill and give yourself a break.
Yeah it happens, like yesterday now I just couldn't do it no matter how hard I tried so I decided to to rest, but today I'll need to get back to writing.