From a Prompt from my writing group:
There needs to be difficulty so we have something to strive for . . . or against.
Difficulty can't mean impossibility or we would be too discouraged. Yet the difficulty must be real or we fool no one, least of all ourselves.
The depth of the feeling of accomplishment is commensurate with the difficulty we have overcome in attaining our goal. This cannot be determined objectively; what is simple for one is challenging for another. But then there's the risk of running into someone who has appropriated the motto: You don't have to lift a finger if you can prove you're all thumbs!
Overcoming formidable tasks is reserved for one of a kind labours of love, not routine housework or yard word. No, it must be something for posterity; something to hang on the wall of a public building, or entered in the record books for all eternity. But that leads to the query; is it useful, does it help humankind? With artistic endeavours, who is the judge? Some inventions, like the ubiquitous combustion engine have been both praised and cursed, perhaps particularly as they have lingered on past the date when some more environmentally friendly substitute should have been found.