NEVER.
NEVER quit.
Pain and suffering are always temporary. And failures don't make you a failure. Quitting does.
NEVER judge a book by its cover.
Don't judge anyone before you know their character and present circumstances.
NEVER assume anything about someone or a situation, unless you know without a doubt that you are 100% correct.
NEVER underestimate anyone or look down on anyone.
You never know what an individual is capable of doing.
There could be a world-renowned author, successful business leader, or another Bill Gates in your mist, and you don't even know, because the individual isn't there yet.