Nat Rutherford writing in BBC Future:
...Epicurean happiness is a matter of being a good accountant and minimising pain in the most efficient way possible...
But the accountant’s view of happiness is too simple to reflect reality. Friedrich Nietzsche, in The Genealogy of Morals, saw that we do not merely endure pain as a means to greater pleasure because "man…does not repudiate suffering as such; he desires it, he even seeks it out, provided he is shown a meaning for it, a purpose of suffering". In Nietzsche’s view, pain is not alleviated through pleasure, but instead through meaning...
That is why mountaineers and marathon runners - like all of us at one time or another - can rationalise the pain barriers they go through to keep going.
A life of meaningful pain then, might be more valuable than a life of meaningless pleasure. As if it weren’t hard enough to work out what happiness is, we now need to work out what a meaningful life is too."
That is the real challenge.