While there is some truth to what Ariana says, scientifically, and she gives one example from FDR, who was a manufacturer of ideas, I would argue the most difficult tasks in history were achieved through the strength of will.

I'd also observe Elon is paying the price for setting out to do something extremely difficult, and though it appears that he's losing right now, he'll come out on top as long as he stays the course. Taking a long vacation, though it may be the best thing for Elon's health, is arguably not the best thing for the company right now. A long weekend is probably in order, but I hope Mr. Musk can find the strength to keep doing what he's doing because it's working (sans the late night tweets and poor choice of Grimes' so-called friends).