Spent the last 5 hours writing…SCP stuff. None of it's good. Does anyone else get this? I should probably get some sleep; It's 2am.
Everyone hits writers's block at some point. As such, it's probably a good idea not to spend hours and hours in succession writing unless you really feel inspiration spurring you on—otherwise, you're more likely to become fatigued and disappointed.
Eat something without doing anything else at the same time, read a short article, go for a walk, look at the clouds, whatever. Take a break. Don't automatically assume that you need to generate good material right off the bat.
As it is, I've always believed that writing should be an enjoyable process. If you're too concerned about the end product, some of that fun can be compromised.
Wait for inspiration to strike again if you're hitting writers' block. Don't dwell on it too much and go find something else that's enjoyable to do, or just try writing something different.