The Will to Power wasn't Nietzsche at his best, it was Nietzsche at what his fascist sister thought was his best. That said (and admitting that I love Nietzsche), I think it should be evaluated on his terms, as whether it's a useful thing to believe. If you're going to experience hardship (and you are), do you want to do it expecting to endure or to be ground down? If Nietzsche's bombast turns you off, try Marcus Aurelius instead
Neitzsche didn't lead an easy life, and thought this was a useful enough thought to paraphrase in his notebook. (And so did Aurelius, I'm sure; if it's possible to trace where it originated other than "everyone says Chrysippus, because of course they do" I don't have the time, education, library or inclination to do it). I think so too.Unhappy am I because this has happened to me.- Not so, but happy am I, though this has happened to me, because I continue free from pain, neither crushed by the present nor fearing the future