How am I supposed to do all this?, Hints for a frustrated GM Options

[MrSandman666]

Alright. I've had enough. I give up, where's my white flagß There, that handkerchief will do...

Seirously? How on earth is a GM to go about his job to create a good and enjoyable game while staying sane and having something like a life?

As a GM you're supposed to know ALL the rules or else your players (who know only the rules concerning their character) will use them against you. Most of the time it's not even malicious. It's just that they know their stuff and they're good at what they're doing. In order to be match for them, however, I must know all that stuff as well or they'll bust my plans. This means I have to know all the possibilites of about four or five character classes.

As a GM you're supposed to know any run by heart (and preferably two or three runs at once, in case you finish early or the players decide to simply not accept a job that looks a bit daunting). You're also supposed to change the run on the fly as the action unfolds, improvise and rewrite and STILL keep it a great story with balanced opposition that is challenging but not overpowering. Of course ideally you shouldn't plan a run at all in order to not railroad the players. But then again you have to make sure that every player is equally involved and always has something to do (in the game!) and gets his five minutes of fame.

As a GM you're supposed to be able to know every scene in deepest detail, have maps and everything ready for handout (or at least in you head, so you can scetch them during the game). You're supposed to populate every scene with fleshed out NPCs, each with a distinct character and personality, of course with full stats and equipment lists. You're also supposed to come up with the interiors of every building the runners decide to stumble into, no matter whether it was planned or not.

How am I supposed to do all this? You need a supercomputer or two to do all this stuff!
I'm sorry, I'm a bit bitter right now. I mean, for some reason I never get to play. I'm not complaining. Not really. I mean, yeah, it would be nice to play every now and then but i can play online. And until recently I did like to GM. But the real reason I'm always GMing is probably because I'm the only Shadowrun GM I know. Of course I could go out and try to find people in stores, but I've had some bad experience with that. I find it more enjoyable to play with my pals.
Anyways, I'm disgressing... Where was I...
O yeah, how am I supposed to do all this stuff? I would have to do this as a fulltime job in order to be able to read all the books, learn everything there is to know about the sixth world, know about all the rules, have enough runs and NPCs at hand in order to improvise and get enough practise to be a halfway decent GM. Unfortunately, nobody pays me for that kind of stuff!!!

My whole point in this post is:
How do YOU do this? Fellow GMs, please help me out! What is the solution? How do you manage to deliver an enjoyable game? Are you an Immortal Elf who has all the time he wants? Are you a millionaire so that you don't have to work and can devote all your time to studying Shadowrun? Are you an AI on a huge mainframe?
Help! Please!