Best research I can come up with at the moment suggests that this Twitter “Top Retweet” comes not from Shakespeare, but from someone named Steve Rubenstein. I have no idea who this is, perhaps someone could tell me. A magazine editor of some reputation?
What I find amusing in cases like this is to see when the quote shows up on Yahoo! Answers. If you’ve ever needed a reason to prove why community-sourced answers are as good as you pay for, check it out. The user is smart enough to ask, “If this is by Shakespeare, somebody tell me the source citation.” Best answer, chosen by voters, is a simple “It’s by Shakespeare.” An entirely wrong, by definition, answer. I don’t know what’s more annoying, the person who answers the question incorrectly just to get whatever points are offered (depending on the engine), or the people voting for it as a good answer.