Get active! Agitate! At least actively propose and defend all suggestions towards the betterment of working people. The establishment thrives on passivity.
I do wonder how effective this would be if for example a multinational can simply withdraw from Belgium or even the EU :-( Even if the argument was made that it was more efficient or at least not less efficient than the status quo, a lot of these companies have a very heavy US-biased view on work-life-balance (see for for example the current RTO initiatives as well).
I found that even one additional hour per day to spend on family and enjoyment was improving my work output in a way that it almost negated the one hour of worktime lost.
It may be depended on the type of work, but many of the trials being held around this seems to point out that production or quality doesn't lower and general well-being increases. Although I'd argue that a reduction in production isn't really a problem: we're very productive in our country as it is; (over)production adds to waste and pollution; and any shortage in production can be compensated by just hiring more people.
I'd honestly prefer the four day workweek, as in four days of working eight hours. But seeing as the employers' lobby and their cronies will never let that happen, some additional holidays would be nice.
I think it depends on your personal state of mind. Some people might enjoy being deconnected more and others just the additional 'buffer' of time around worktime.
I don't enjoy working to begin with in the current economic system in any way. Most work, including mine is busy work to keep the infinite growth bubble from popping. Keeping the bubble alive is why a four day workweek will not happen any time soon. There's a shortage of people able to do the work that's needed. So decreasing the hours these people are available goes against the self interest of the rich.