If you do not know where you come from, then you don't know where you are, and if you don't know where you are, then you don't know where you're going. And if you don't know where you're going, you're probably going wrong.

I don’t know what to do,” he said. “No harm in that. I’ve never known what to do,” said Rincewind with hollow cheerfulness. “Been completely at a loss my whole life.” He hesitated. “I think it’s called being human, or something.

...Granny Weatherwax, who had walked nightly without fear in the bandit-haunted forests of the mountains all her life in the certain knowledge that the darkness held nothing more terrible than she was...

Commandment #1: Believe in yourself. Commandment #2: Get over yourself.

They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance.

It's vital to remember who you really are. It's very important. It isn't a good idea to rely on other people or things to do it for you, you see. They always get it wrong.