I assume you're young, and this is the right attitude if so. Not that it becomes "wrong" as you age, but many people cannot maintain it, through a combination of burnout, less energy, just becoming jaded, or having other interests and priorities.

I'm past middle age and hard work is no longer its own reward for me. Forget a 4-day workweek -- I work about 4 hours a day. Any more than that and it's just going through the motions, there's no additional productivity. I will still occasionally get really into something and find myself still engaged after many hours, but it's rare these days whereas it used to be common. However I do not think I would have liked this as a 25-year-old. At that age I was excited, still learning, and full of energy. A 4 hour workday would have felt like I was just getting started.