Earlier quoted context omitted.
I read that differently from you. I think he's sad because they _do_ go to the effort of hearing the cuckoos, but they're rushing. They're not fully present, and so they don't get the full experience. He, by contrast, is very present in the things he does. That he doesn't choose to do many things is a different topic.
Is it different, though? Can you do things that deeply without limiting the number of things you’re doing?
Something can be gained by not stripping away boredom, but instead "savouring" the moment to see where it leads (essential for creativity).
Then there is the idea of taking a cold shower as first thing in the morning to tell your subconscious to better not be to comfortable, and prepare "properly" for your day ahead (without "expectation" of comfort). Eating the same supper is a similar spirit and strips away the comfort and thinking that "one has an entitlement to something".
See also the Stoic philosophy etc.
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[1] this is a truly fantastic book if anyone was looking for an unsolicited recommendation https://en.wikipedia.org/wiki/The_Discovery_of_Slownessfrom the wikipedia link:
> "Slowness" — in German, "Langsamkeit" — had, before Nadolny's novel been primarily associated with mental retardation. In Nadolny's world, however, this seeming disability is in fact a powerful asset; the possessor of "slowness" can afford to wait, because he must wait. As a result, he attains victories unimaginable to the more "hurried" multitude. Nadolny's choice of a hero is apt in this regard; certainly the historical Sir John Franklin was never known for his mental alacrity, but beyond that, his "slowness" is more of a post-modern conceit. In a manner reminiscent of Roland Barthes' "autobiography" of Jules Michelet, Nadolny's Franklin is completely consistent with the known facts, all impeccably researched. Yet interwoven with the truth there is an entirely fictitious construction of Franklin as "slow," ranging from an imaginary ball-game in which the hapless John always arrives several seconds after the ball has departed to a fictitious re-creation of Franklin's efforts, at the height of Admiral Horatio Nelson's naval battles, to find and shoot a sniper from atop the masts of an enemy warship. By waiting, without panic, and carefully noting the angle at which the sniper's shots have been discharged, Franklin pinpoints his location and takes him down with a single shot.