Is There a Limit to How Much You Should Do Per Day?

I felt somewhat liberated in recent years by this knowledge that, gosh, if i accept that i'm really only capable of three or four hours of true, intensely focused work. Whereas back in the days when i thought i really should be generating eight to ten hours of work, i would always feel like somewhat of a failure. An i probably still doon a lot of days, feel like i didn't get enough done. But i do think it's liberating, isn't it, to sort of just accept a somewhat more humble view of what we're capable of? And there's some really robust u social psychological evidence for why this is.