I've done light-to-moderate physical work and would prefer 4 10-hour days for that. Office work in front of a computer, including programming, I can't realistic

I've done light-to-moderate physical work and would prefer 4 10-hour days for that. Office work in front of a computer, including programming, I can't realistically manage 5 five-hour days of actual, productive work. Not week after week, consistently. With more rest and an interesting task, yeah, I can do 8-10 hours in a day, for-real. Every now and then if I just happen to have a great day, yeah, maybe. Otherwise, god, it's draining as hell, in a way "boring" or repetitive non-back-breaking physical work just isn't (for me, anyway). Story may be different for the really body-destroying physical labor, but the lighter stuff is less tiring than office work, to this particular worker, and cutting it from five days a week to four with the same number of hours would be my preference if I were back in jobs like that. Meanwhile I'd love a 4-day 6-hour schedule for programming. Maybe I'd actually manage to do focused work all the scheduled hours, that way.