First and foremost lets be clear, this entire hobby is bullshit. The GM bullshits a story about people and places that never happened while the players bullshit being great grand heroes and I love every second of it. When I say bullshit obviously I'm not meaning it's crap or badly done, but that it's all one great big shared lie that forms real memories and friendships. We all had that friend as a kid that was full of BS, claiming his dad invented this or he has a friend from another town that did that and to be honest must of us knew he was full of crap but if the story was awesome enough that we wanted it to be true we would still "believe" and roll with the punches. To me this is one of the biggest parts of GMing and, while parts of it are mentioned here and there, I don't see nearly enough time dedicated to emphasizing its importance.
As GMs its our job to give our players the best quality BS we can. It's up to us to make up a story that sucks everyone in, filled with events and places and people so awesome or interesting that no one cares if its all made up crap. Alternatively, it's the players job to BS their character. Lots of GMs I know kind of scoff at players who have issues making entertaining or unique characters as they are making "entire worlds", but I will give credit where credit's due and let any players reading know that it definitely can be just as hard. While GMs have to BS wondrous events and characters interesting enough to talk to, the players have to walk the tight rope of telling the story of just one guy (or girl, or lizard, etc.) that's both interesting enough that everyone else is entertained while also not going so over board that everyone just rolls their eyes as "Gragnok the Barbarian" saves the day with none of your puny help because he is just that awesome.
Gaming is something very special, but also something very strange. At its core it is all just a giant shared delusion that everyone is willing to buy. I've heard a lot of people call this "buy in" with them talking about needing to make sure players will buy into your themes, or genre, or setting, what have you, but honestly it's all about if the people at your table are willing to buy into your specific brand of bullshit and it you're willing to buy into theirs. Personally I think this is why those longer running groups of friend/gamers tend to flat out run better games than pick up groups or con games. That's not to say those are bad games (I have plenty planned in the future for helping with games where you might not know a single person), but truly great games grow from friends sitting around a table bullshitting each other.
Notice I said "Friends" and not just gamers or players, that's because to me if you want games to run as smooth as they get then you need to be playing with people you do more than just game with. This can be as simple as talking about things other than gaming in your free time all the way to as invested as your best friend. The point is that they aren't just your players and you aren't just the GM. I've tried joining online games where GMs run things like this and, honestly, it feels more like a business relationship than gaming. This is a medium about creativity and expression and neither of those are fostered in an environment where it's your "job" to shit down and roll dice or act out some other guy's story as he sees it. It comes from being relaxed and being free to sometimes do something stupid and familiar enough with people that you know what they are willing to run along with and what's just going to fall flat.
Th point is, after all this rambling, too many people seem to forget that its all a game. Sure some games are much more serious than others, and yes it can take a lot of work, but at the end f the day its about friends sitting around a table telling cool stories that happen to have rules and dice and sometimes maps. Sometimes things will fail, lots of times things will go wrong, but relax and roll with it. Plus, when it's with friends, you can always try something new next week f it all falls apart. So when you're sitting there planning a session or even worse building the beginnings of a campaign and you start to stress if things are too forced or if this or that isn't fleshed out enough just remember that at it's all just bullshit.