I'm convinced that humans can't (or at least, shouldn't) actually work 8h a day. I'd argue that taking an hour to exercise or walk during the work day and working maybe 6 hours would make people more productive and happier than just working 8h.
Unfortunately management thinks that lines of code written or token usage or seats in butts or {insert random quantitative metric} equals peak productivity.
Relatedly, I'm convinced that humans cannot achieve any form of peak performance in any domain (athletics, art, business, community organizing) without consistently going for walks. We're all aware of the programmer working at a problem for hours, going for a walk, sitting down, and then elegantly solving the problem in a few lines of thoughtful code (haven't we all experienced this?), and here is an example in another domain...
I have never been at my best rock climbing performance without a substantial amount of walking; even if I am training well, eating well, sleeping well, climbing with others, and super enthusiastic, the element of walking is for some reason critical.
My suspicion is that the human body is designed for walking (eg, we are upright, our shoulders adapted to swing the arm) and that myriad processes simply will not occur or will not occur optimally without walking. I believe restoration on a cellular level is enhanced by walking, that various cognitive and sub-cognitive processes are aided by walking, and that many of these processes sync up with a sort of supermodular (https://en.wikipedia.org/wiki/Supermodular_function) effect when walking.
I found that my best 5-6hrs a day are enough to make the work that I could do in 8hrs. With less time I'm also forced to prioritise and prune more heavily, but at the same time, there's stuff that in the short term is always a bad idea to automate and some dumb grunt work can get it done, in which working for longer gets more done if you only care about the short term (like management loves to do).
I argue that taking a minute or two every hour or so to do a few reps of an exercise clears people's thinking, lends perspective, provides fresh ideas, is great for general mental health, and hence, makes people more productive and happier than sitting for 8 hours or more and going to a gym after.
Small training sessions at work, throughout the day, are also great to build a strong team spirit and feel pumped all day. Unfortunately, people tend to rigidly compartmentalize rather than seamlessly integrate physical activity into their lifestyles.
I tend to agree. I had a gym trainer tell me that the best way for me to learn to do 100 pull-ups in a row (ie the Murph challenge) was to do a few pull-ups every hour or so (grease the groove) until I can do 100 in a day. Then just keep improving from there.
So it's good for strength too!