I've "corrupted" (from the point of view of GDP productivity and such) a lot of people into asking for (and mostly getting...) a 32h/week work schedule.
I've been doing it for almost 8 years now, and at this point, it's simply a non-negotiable in any sort of employment discussions (that, and not carrying a pager). I work Mon-Thu, 8h/day, and I'm generally unreachable Fri/Sat/Sun (doesn't mean I won't put in a long week on rare occasions, but think "once a year or less" sort of frequency). The work/life balance is far better, and it aligns better with my family (the local public school is only Mon-Thu as well).
Just ask about it. I know some people who've managed full pay for 80% hours, but generally "80% pay for 80% hours" is entirely reasonable too, and I've found (as a rather extreme DIY sort) that the extra money isn't missed, because I have more time to do things myself on the weekend. I can practically spend quite a few Fridays a year doing major DIY work, and come out ahead.
I genuinely cannot say enough good things about it. Try it. You won't miss 40s.