That first blank page

My problem is putting the story into print.
Ideas at the moment are no problem , but sometimes they dry up. The best time to think is when walking the dog, but at the moment I have a new puppy so I have to keep my eyes on him 24/7.
My problem is that even though I'm retired I usually only get to write in peace late at night when I'm often to tired to write.

There's a famous author (I forget who) who said that the hardest part of writing is convincing people that when you're staring blankly out of the window, you're actually hard at work...!