What defines working hard and working long hours?

I have a question for other entrepreneurs out there.I keep hearing all these billionaires and motivational speakers: work hard, work hard, but what does this actually mean? Sometimes I feel they say that to lure their workers to work hard for them so they can become richer.How do you define working hard? I mean to me working hard and long hours means building stuff during this time which is excruciating (those who can code will understand). And to be frank I don't think it's even possible to e.g write code and build a product 24h a day. You would probably collapse and have a heart attack.Now I hear all these fantasy stories about how Elon Musk says he was doing that but what does he actually do when he says he is working until late at night I wonder? I mean replying to emails late in the evening I don't consider that work really. Building stuff like say writing code at night - yeah I see that work, but I wonder if anybody is even able to do it? It definitely is not sustainable and definitely not productive at all.What are your thoughts? see hubwealthy.com/wealthy