Kudos for the OP's perspective on game abandonment. Most threads about GM abandonment are by players who complain that a GM dares to put their own enjoyment ahead of theirs (at least that's how I see it ). Anyways

One important part of running a game is realizing what parts/aspects of GM-ing you enjoy the most and the least, and then focus your games on the former while minimizing the latter. Of course, if everything, (from crunching encounters, coming up with cool settings and plot twists, to rp-ing NPCs etc) looks like a tedious chore then its time to take a rest, until at least one of these things looks interesting again. Since this is a hobby you don't owe anyone anything, especially considering that as a GM you already put more effort and time into the games than your players.

If really no-one else is picking up the mantle as DM or they absolutely abhor rotating GMs, then focus on GM-less games, but my guess you simply haven't made it entirely clear to your players that you don't want to GM anymore.

I'll make this short.

If you are feeling bored and tired of running games, just tell your group exactly that. Ask if anyone else is up for running the games for awhile. If not, then it is time to bring in board games(I recommend Arkham Horror!) and other forms of wasting time during friendly gatherings. The original reason to game is to have fun with your friends. If fun is gone, you are dragging yourself through the mud.

If they are only interested in you running and nothing else, then there is a problem with the group dynamic and game night is probably over for you. This isn't an unusual problem with tabletop groups. I've went through this many times. Switch GMs, switch types of games, or eventually move on.

Take a break as long as you need, enjoy yourself with other things. That's all there is too it

Do not accept any guilt trip that any player may attempt to foist on you.

My DM is in the same situation, started DMing about the same age and same way as you. A few years ago, he also hit a wall.

Part of the problem is the players he's been playing with for 10-15 years now are all more or less turning munchkin, min-maxers or rule-lawyers. They're still friends, but it's sometimes difficult to play with guys who know the system better than the DM. For example, he didn't quite embarked on D&D 3.5, so when the rest of the group convince him to run a game in the new system, he was afraid by the amount of splat avalaible and the powerhouse the players came up with. And without talking about the concepts some players deadly wanted to try, even if those concepts didn't fit with the rest of the party, and inevitably made the campaign completely sidetrack.

Last autumn, he gathered a few friends, including some complete newbies, and ran a good old AD&D Ravenloft, his favorite setting. And he had a blast. He got his DM instinct back, so much that he planned running a game with his old munchkin friends.

So that would be my advice: go back to the basis. Do something YOU like, the way YOU want it.

I've actually had this same problem, and I think you're getting a lot of good advice here. My wife (one of my players) noticed that I was getting frustrated while planning a game, and when she talked to me about it, I said that I wasn't enjoying planning, but that I still wanted to play, and to hang out with friends, and that if I didn't run anything I was afraid that the group would fall apart.

What she said was basically encapsulated by what Orchomenos said:
For me, that meant getting back to basics, taking more control of a story than I had been (her words were that the game needed one DM, not five DMs), even if it meant sacrificing some of the player freedom I had been allowing.

We're just anonymous talking heads on the internet, so it's up to you to decide what to do- but I think if you're burned out on running games, maybe you should tell your group exactly that, and say that someone else needs to step up and try a game, even if they need help running it, because you need a break. If they're not willing to do it, then suggest board games or play something that doesn't need a GM, or even just take a break for a little while. The last one (taking a break) is the hardest, because it will usually mean that the group stops playing together, as people will find other activities to take up their time, and then have to change gears from those activities to come back to gaming.

If you're open to it, there are stores that run public games, and you should be able to jump into a weekly game and just relax and let your brain unwind.

Hope it works out for you, Mick.

- Logain

If planning the encounters is becoming the major chore, I would recommend looking into published adventures and tweaking them to your needs. This can also be a way to get one of the other players DMing for you. Choose the one who seems most likely to be a good DM. Take them to a convention or hobby shop, pick out a low-level pre-made adventure and say, 'Wow, I'd really love to play IN this one. Have you ever tried running one of these?"

They might be more up for running a game if they don't have to build it from scratch first.

The first thing I always consider is how excited I am for the game. If I'm not, I tell the group, "Hey, I'm really bored of this game/rules system. I want to switch to something else." Have in mind a game you are excited about.

There's nothing wrong with leaving a game on "pause" as it were, and coming back to it later. In fact, the games will be more enjoyable for everyone if you do only leave it for when you're excited to run/play it.

One thing i've noticed is that people who enjoy DMing actually often end up in a player role because of some hump they can't get over to start DMing.

If you encourage them in it, and can pick them out of the group, and give them a bit of help on their first couple of adventures/ideas, as they usually hit walls early on, once they get up and running they have huge fun doing it and usually at that point you get to play at least some of the time.

The 'hits walls later in DMing' and 'hits walls earlier in DMing but not later' is probably why they usually end up just playing, as they don't get over those early walls, while people who have no early walls often end up running into a massive one later on.

Have you considered running a different game? A lot of newer games like the FATE games and Cortex Plus games do a good job at taking a lot of the load off the GM. Just a thought...