Combating GM Burnout

Being a GM can be tiring.  Not that its not brilliant and a lot of fun but all of us have times when you look at the prospect of being the game master for the next game with a sense of trepidation.  It could have been a bad day that soured everything or just a sense of lethargy and sloth that overcomes you.  Hell, it could even be the shitty onion and coffee breath of the gamer on your left.  It really doesn't matter.  What does matter is how you overcome it to have a good game anyway.  Sometimes you can't but you'll have a better chance if you keep a couple of tricks at your disposal.

• Before you start, take the time to dump everything that has happened for the day.  Just cast it aside.  For the next couple of hours, nothing that occurred early will matter.  When you walk in to game, act that way, even if you have to fake it.  You might find, in doing so that it actually happens if you let the flow of the game carry you.
• Meet your level of preparation.  Its critical you be ready to the extent you like to be so.  Some GMs are wonderful at extemporaneous gaming.  Others need four books, an atlas and a hundred pages of notes to do the same.  Even others fail to GM outside of the framework of a pre-built, minted module.  Nothing is necessarily wrong with any of these types (though I do have preferences and opinions to each) but they each have a different level of preparation attached.  Make sure you meet that or it will make your game harder.
• If your burnout stems from your plotting or the very game itself, such as the direction its taken or the characters within it, the best advice I can give is to come clean with your players.  You might find they too are just as fractured.  I'd suggest hinting at it and a little subtlety at first in case they are not.  Invariably one person is going to love it no matter how the others may hate it so be prepared. 
• Burnouts that stem from a drying up of ideas are easier to fight.  Take some time off.  Give it a break for a little while.  Play a different game, read some books, take a walk or watch some movies.  Find the zone that inspires you and get in it.  Decorate your room in things that get the creative juices flowing or go somewhere they shakes up the idea percolator.
• Player-induced burnout or tiredness can be tough emotionally.  If you have a single (or more) player that is getting you to hating the game, then they need to go.  Especially if they can't take the hint (if you are nice enough to give them a chance to change).  I usually give someone 1-2 strikes and then they are out.  Gaming is a stress relief for me and stress inducers get the book quick.
• You're the GM.  If the current game is a drag for you, take a break, go to the bathroom and look in the mirror. Repeat the first sentence.  Take a few breaths and then repeat it again.  Ignore what is going on, discard your plots, and throw player desire to the winds.  What do you want to do?  Repeat it to the mirror.  Then take the idea that percolates to the top and write it down.  Repeat this process until you start feeling stupid or draw a blank.  Look at your little list and then walk back to your game and make those happen.  Don't worry about reactions, just implement it and enjoy the moment.  If it wrecks your game, cast it as a dream, drug induced fancy or any number of other tricks.
• Challenge another player to GM.  It doesn't matter who or how: subtle is best though not required.