For rational beings like humans, only the irrational is unbearable. What seems rational becomes bearable. Physical blows aren't naturally unbearable. How do we know? Look at how the Spartans endure whipping once they learn that whipping serves a rational purpose. Even hanging yourself isn't unbearable. Once you believe it's rational, you'll do it. In short, if we pay attention, we'll see that humans suffer most from what seems irrational. And we're drawn most to what seems rational.
To the rational animal only is the irrational intolerable; but that which is rational is tolerable. Blows are not naturally intolerable. How is that? See how the Lacedaemonians endure whipping when they have learned that whipping is consistent with reason. To hang yourself is not intolerable. When then you have the opinion that it is rational, you go and hang yourself. In short, if we observe, we shall find that the animal man is pained by nothing so much as by that which is irrational; and, on the contrary, attracted to nothing so much as to that which is rational.