So go on, get angry. But keep your mouth shut and go do your work.
Art that only comes from the head isn't any good. Watch any good musician and you'll see what I mean.
When people give advice, they're really just talking to themselves in the past.
Your brain gets too comfortable in your everyday surroundings. You need to make it uncomfortable. You need to spend some time in another land, among people that do things differently than you. Travel makes the world look new, and when the world looks new, our brains work harder.
The best advice is not to write what you know, it's to write what you like.
It sounds a little extreme, but in this day and age, if your work isn't online, it doesn't exist.