They say you spend 1/3 of your adult life at your job.
It's meant to scare you and make you aware that life is also elsewhere but your job.
But 1/3 doesn't seem right to me.
It's obviously based on the idea that you have 24 hours per day and then 8 of those are work = 1/3
This is not a fair calculation - at all. I would argue it's more interesting to calculate free time you actually can spend on what you want.
So then first of all remove sleep = 8 hours
Then remove commuting. I guess an average is = 1 hour
Daily chores that you have to do. This depends but I would say = 2 hours
So work + sleep + commuting + daily chores = 19 hours.
Now you have 5 hours left per day spent on what you choose.
Of course within these 5 hours you are not necessarily free, for a possible million reasons, but at least it's a benchmark of free time per day.
We are missing something though: The weekend.
Some of us are priviledged to have both Saturday + Sunday off.
So that would need to be calculated in, and distributed on the average daily free time.
This would roughly be 24 hours x 2 days - 2 x 8 hours sleep - 2 x 2 hours chores - 5 hours free time x 2 days = 18 extra hours
So if you take 18 hours + 25 hours (7 days x 5 hours free) / 7 days = 7,6 free hours per day on average.
7,6 free hours is not that bad. But it still means you spend around 50% of your awake life on work. Not 33%.
What is the optimum? What should you strive for? There are moral implications to this. Our ancestors worked way harder than we do now on average to give us this life. So I think it would be weird and ungrateful to just stop the progress by working way less and thereby reducing the progress in society. We have so many more injustices globally to fight for, and so much more potential in humanity to become truly great and caring. At this stage in our development (pre robots and AI) we need everyone to join that fight and take part in shaping the future. Every job is important. Every piece of hard work is important.
On the other hand we should work towards a future where we work less and let machines do more. So I am for a gradual downgrade in work hours and conditions. But not before we can actually sustain it.