Thanks for the answers. What has worked for me is a combination of a few of the answers.
We have a bunch of inner voices telling us to do different things. GTD helps a little with this, but over a period of time those voices become loud again.
"Check email now, you don't have checking email written in your GTD!"
"You said that we wanted to go on a tour of Italy, when are we going to do that?"
"The table is dirty! It's been dirty for 3 days! Clean it now! We can't work on a dirty table! Ants will get into your laptop! And there's things rotting in the fridge!"
"Hey, you paid $40 for that game, remember? It would be a real waste if we never finish it!"
"Are you going to sit there getting fat on video games? We paid $80 on running shoes remember? You haven't ran in a month!"
GTD alone will track these, but even with weekly reviews, those issues will feel neglected. The more creative we are, the more these conflicts arise.
Committing 99% to something is mentally fatiguing. But 100% commitment is easy. Once you make 100% commitment to one thing, the other voices immediately shut up.
They solution is to make a 100% commitment to something. Write it down. Week Plan, as suggested, is a good solution. Planning too far ahead risks plans being shot down, especially when it involves someone else. Planning something for just one week works. There also needs to be GTD, but that GTD should be converted into a schedule.
To turn it into a 100% commitment, have a punishment should those plans fail. Donate a small bit to charity every time a plan fails (or an anti-charity). Even the slightest, concrete punishment works.
However, relaxation must be planned as well. Computer games go best uninterrupted. Movies are best with a friend and when fresh in the cinemas. Without fun, there's no point to work.
Treat enjoyment with the same seriousness as work. Plan it out. A day with the family, a day with friends, or just a day to yourself. Set aside the same fine for not committing to that fun. Without committing to fun, a part of yourself will be yelling at you to procrastinate.