Writer's Block

Is writer's block real, or a cop-out? Is it a real affliction, a real blockage and obstruction of one's urge to write, or is it all simply in the mind, an easy excuse for not writing anything?
I have been sitting here for THREE HOURS trying to write something. Do you think I've written nothing? Not so! I've written many things, started many things! But everything I started amounted to nothing. Garbage! So now I'll have to admit that I have written garbage in the past, and thought it was good. But that's not the problem. If I could have, tonight, pumped out 1000 (or even 500, or 200, or 50!) words and thought they were good, I don't care if it's a delusion!
Let's say you wrote some pieces that you were sure were good, and six months later you read them again and they were still good. And you may have gone on for an extended period writing pieces that you really believed were good and well done, and all that jazz. But then one day you tried to write something, and no matter how long you hacked away at it, nothing worked out. Usually, in the past, you might have to sit there for up to an hour or more, stabbing away at the keys, and deleting, and beginning again, but usually your muse sauntered in at some stage and took control, and then it was all downhill.
But what happens when your muse goes on holiday? What happens when, three hours later, you are still sitting there poking away at the keys and nothing but garbage appears on the screen? And what if that goes on for days, and even weeks? What then, eh? Is that all in the mind? No, it's not. Writer's block is real, and it really sucks.
So how does one deal with this nasty bane of the wordsmith? It seems to me that the only way to deal with the rotten thing is to go boldly back to the machine every night, every day, completely disregarding any depressed thoughts of futility you may entertain, and force yourself to put some words down. Any words. Just start stringing them together! Sooner or later your seemingly forgotten ability to write will return!