Other than "be yourself", what's the best advice you've ever received? 
Can be funny or serious, You can post more than one.

"How you see yourself is just a habit, not a definition - it's all up for grabs."

That changed my life (or began to...), along with "Why should other people have to suffer in the cause of your development?"

And (said with a slow shaking of the head by my Yorkshire friend) "Take my advice: don't take my advice!"

"If you give someone twenty dollars and never see them again, it is probably a good thing."