Here's the quote from Brenda Ueland about rejecting the idea of what you "should" (or "ought" to) write:
“Yes, you must feel when you write. You must disentangle all ‘oughts.’ You must disconnect all shackles, weights, obligations, and duties. You can write as badly as you want to. You can write anything you want to . . . Just so that you write it with honesty and gusto and do not try to make somebody believe you are smarter than you are.
As you write, never let a lot of ‘oughts’ block you: I ought to be more humorous, more leftist, more like Ernest Hemingway, more bitingly satirical. Then it shows. That spoils it. It will not be alive, but dead.” –Brenda Ueland, If You Want To WriteAnd once again, here are the timeless "Rules for Writing Practice" designed by Natalie Goldberg and applicable to more than just writing, perhaps even to life itself.
1. Keep your hand moving.
When you sit down to write, whether it’s for ten minutes or an hour, once you begin, don’t stop. If an atom bomb drops at your feet eight minutes after you have begun and you were going to write for ten minutes, don’t budge. You’ll go out writing.
2. Lose control.
Say what you want to say. Don’t worry if it’s correct, polite, appropriate. Just let it rip.
3. Be specific.
Not car, but Cadillac. Not fruit, but apple. Not bird, but wren. Not a codependent, neurotic man, but Harry, who runs to open the refrigerator for his wife, thinking she wants an apple, when she’s headed for the gas stove to light her cigarette. Be careful of those pop-psychology labels. Get below the label and be specific to the person.
4. Don’t think.
We usually live in the realm of second or third thoughts, thoughts on thoughts, rather than in the realm of first thoughts, the real way we flash on something. Stay with the first flash.
5. Don’t worry about punctuation, spelling, grammar.
6. You are free to write the worst junk ever.
7. Go for the jugular.
If something scary comes up, go for it. That’s where the energy is. Otherwise, you’ll spend all your time writing around whatever makes you nervous.