I think most of us have been there. You know that you have a game in 4 days and that you need to prepare ... and yet somehow you can't find the motivation to sit down and just write. I've just gone through it before my last session - the 5th in a line of about 15 I have mapped out for my 4e campaign. It wasn't even that I didn't know what was going to happen - it was just I couldn't find the drive to sit down and put it down on paper.
Finally with about 36 hours to go I managed to sit down and start to write. What did I learn from the experience?
1. An imminent deadline is a good motivator - the closer I got to the session the greater my motivation. If you're stuck then plan ahead and make sure your diary is free the day before the session. There's nothing like the fear of having nothing to say to drive you to write. You'll keep putting it off until the last moment so just plan for that from the start.
2. Plan the session in your head - I spent a lot of time thinking about the encounters I was planning to run, playing them out in my mind. I think part of the reason I couldn't write the session was that I wasn't happy with the content of some of the encounters - particularly some of the skill challenges. However as I played them out in my mind, during coffee breaks, bus rides, the soap the Mrs insists we watch together, driving to work and so on I was able to work out how I wanted them to play out. Just the odd few minutes thinking about it was often enough.
3. Get something down on paper - even if it's just an outline, a concept or some keywords it helps and doesn't take much time or effort. When you actually come to write this is a great reference point to come back to and it gives the idea a certain permanancy. Its much easier to develop an idea once you have something written down - even if you end up changing it completely.
4. Short bursts are better than long slogs - don't write for more than a couple of hours at one go. Its much easier to face the task if you know its short, you're likely to produce better quality work and it's easier to fit into your busy schedule.
5. Go freestyle and wing it - get back to the seat of your pants roleplaying you used to do years ago. Have some vague idea of direction, compile a list or names for NPCs and have a trait table on hand to make them more memorable, think of a couple of twists and you'll have a great few hours gaming for 30 mins prep.
6. Borrow or steal encounters - buy an adventure, use one from Dungeon or surf the net and use one written by another amateur DM. Just make sure you read it thoroughly first. I grabbed some encounter groups from the Monster Manual and Dungeon Delve.
7. Remember what it is about the game you love - play to your strengths, the more you enjoy it the more you will convey that to your players and the happier the gaming experience will be.
8. It doesn't have to be perfect - you are not Tolkein, George Lucas or Steven Spielberg so don't expect your adventures to have the epic depth or heartthumping drama you read in books or see at the movies. Take the pressure off yourself. Your group enjoy gaming with you and still will even after they figure out you aren't the greatest storyteller in the world. Just get on and tell your story - it's that story the players want to hear.
I'm sure there are other great ideas out there. Post a comment and let me know what you do when lack of motivation grabs hold of you.