I would argue that _most_ full time jobs probably require too much of us than we should be willing to accept, regardless of if we have energy left over to do anything else outside of those hours.
40 hours per week is more than half of most people's waking hours. That's a terrifying amount of my life to have to spend on something I don't _absolutely love_ doing, and I sincerely hope I can find a way out of it sooner rather than later.
not counting that 40hrs weeks accounts just for working hours. You should add 1hr per day for lunch or equivalent pause, and often 2hrs\day for commute. You easily end up to 55 hrs that is ~50% of your waking time. You should add all is needed to sustain a full time job that requires you to be conscious of what you're doing, so I'd add some routine habits that make this possible, like maybe time to readapt your consciousness from work environment where you just lived and focused thoughts the last 9 hours, as I feel to need. You sell your life when working full time for someone's(something...maybe) else enrichment. Those 40 hours a one give to someone else are the most profitable hours a one have
I agree and we cannot do anything about the hours apart from perhaps trying to find some part-time job, but that is probably not easy either.
So my point was just to not bet full-on on two horses at one. If your priority really is your side-gig or starting your own business, then do not run too fast in the hamster wheel also. Put yourself in a position where it might not be the most fulfilling work, but it serves the purpose of giving you economic room for pursuing your own business.
40 hours per week is more than half of most people's waking hours. That's a terrifying amount of my life to have to spend on something I don't _absolutely love_ doing, and I sincerely hope I can find a way out of it sooner rather than later.