it's funny, though, because it's a huge ramp-up in terms of amount worked. throughout my entire life i've worked smarter, not harder, with the result being that i've probably never had a substantial period of time when i've worked more than 20 hours a week. this is, of course, not true now. we aren't kept track of, and i'm not in a group (i'm working on a firmwide project), so it's certainly not forty, but i'm averaging somewhere between 25 and 30 hours a week.
i feel like i'm unique in having had a life where this is a maximum and far above the average. during my postdoc, it varied, but i probably averaged 10 hours a week of work. of course, with math, it's passive, because problems are theoretically percolating in the back of your mind even as the front of your mind is rockin' out to a hella cool britney spears song (for example), but i actually spent very little time even idly pondering things, especially towards the end when i was feeling uninspired if not disenchanted about academia.
so it's an interesting transition. maybe one day out of ten i either arrive before or leave after my officemate (today happens to be that day); he was hired when i was, and appears to be working at least 50 hours (though obviously my lower bound is my own working hours), trying to get up to speed. i'm, well, not; people probably think that i'm slacking off, but for me, given my life, this is working hard. it's not that i find the work at all onerous; i (usually) do not. i just don't have the stamina right now to work 40, 45 hours a week, even with frequent breaks (which i have intelligently worked into my schedule; it strikes me that i could be referring to 1-week or 5-minute breaks, both of which have this useful effect and both of which i take frequently.)
i mean, i'm getting what i consider to be a good amount of work done. i'm still working smarter, although my brain doesn't click quite as well as it used to (i blame rust, not age; it's gotten better since the end of the era of indolence.) it's just funny a lot of the time how much my parameters differ from everyone else's.