GMs run games and players play. Some people do both, but more often than not everyone stays on their side of the screen. There are a myriad of subtle social forces that encourage things to stay this way (comfortable players, GMs threatened by others usurping their position, etc.) but we're not going to worry about that right now. Instead we're going to encourage you to buck the odds and mix things up.
Both players and GMs stand to learn a lot from trading places. A lot. A whole lot. Players may come to appreciate just how hard it is to GM (whether it's preparation or just keeping things on an even keel for a whole game session), and GMs may be in for a rude wake-up call when they see their own worst behaviors in other people.
Also, starting out as a GM is hard. Far too many would-be GMs ponder some game they want to run for months or even years, but never actually bite the bullet and run the thing. Just pondering is safer, there's no risk of failure, and it's less work too. They'll concoct plausible reasons for the delay, baulking at even running a single game because they haven't prepared enough. “Well I certainly can't run a game until I finish charting the lineage of every royal family on this subcontinent. And of course I'll have to revise the entire magic system…” Procrastination is even easier if there is already another game running to fill the void, so there's no demand forcing them to actually run something.
So how do you mix things up? Start a Run Club.
Here's how Run Club works:
1) Every month (or two weeks, or whatever works) someone takes a turn and runs a game. One-shot, short game. No campaign. No big picture. Just a single game.
2) Everybody who plays will GM. Everybody. This is the core principle of Run Club. You cannot play if you will not GM. That's the pact.
3) When everyone has run a game, the round is finished and you can start over again.
That's it. Simple on the surface, but in that simplicity a number of complex issues are addressed.
Since the requirement is to run a single stand-alone game, planner/procrastinators are called to the carpet and made to deliver (the “good GMs run games” principle). You don't need a continent to run a single game, you need a town or single dungeon at most. Part of that procrastination is certainly fear, so now you get to confront that fear.
Another source of fear for would-be GMs is that they will offer to run a game and no one will want to play. Maybe no one likes the game concept, or worse still no one trusts that you will GM well and run a good game. Players know they are investing their time don't want to waste it. Even though it isn't a written rule, participants in Run Club have a sense that they have already signed up for the process, so there is much more willingness to play in each Run Club game even if you expect it is going to bomb. It's almost expected that many of the games will tank horribly (and they will), but everyone knows it's a learning process so the usual resistance to playing in a potentially bad game (or one in a genre you normally would not like) is diminished.
Reigning GMs are afraid new GMs will supplant them. You're the center of attention, with a crowd of loyal players, and then someone else offers to run a game and everyone is excited to play in it. Were people really bored with your game? Were you doing something wrong? Sometimes they are, and sometimes you were, or sometimes people just want a change of pace no matter how good your game is. Run Club lets other people try sitting behind the screen without threatening the status quo. The reigning GM can let others run games without feeling threatened, and players who might normally be too timid to depose their own GM get a chance.
So be brave. Get your group to start a Run Club of your own. Some games will be surprising, some games will be complete disasters, but all of them will be educational.