Well, I've been DMing continuously for about 10 years or so. I did "burn out" back around 1995, and stopped for about a year and a half in University, then got back into it. I stopped for about 8 months back in 2001 when I met my girlfriend, but otherwise it's been continuous.
I've tried playing, but in my area, I've developed a bit of a rep....none of my players want to run a game so I can be a player....they keep bringing friends from other groups over, and asking if they can join mine as players.
So, since it seems I'm stuck DMing, I switch up games. I'll run one campaign for 6-12 months, then switch to a different one....or even run two campaigns simultaneously....do 4-5 sessions in one, then 4-5 in the other. I find by doing this, when I switch, I get all excited with ideas I haven't been able to implement in the first game, and bring them into the second.
Right now, I'm kind of jumping back and forth between Planescape and Swashbuckling Adventures...before that, it was Planescape and Wheel of Time. I find when I switch over, my energy level is way up for a while. Then, I get the itch to switch, and we go back to one of the other campaigns.
This may or may not work for others. Seems to do the trick for me.
Banshee