Aggressive prioritization. The hours you work don't matter. What matters is if you get the job done. Be effective. Thankfully (i think) you're in a position to be judged on your effectiveness and not other criteria. As you only have to convince yourself, you co-founder and the rest of the team. It might be a chance to change the culture too. It's not about hours worked. It's about whether the work helps the company. Lots of effective hours pays off. But some effective hours are worth more than many many wasted hours. This is something that often gets lost.
Delegate to others the stuff they could do. Do only what is important. Be flexible with yourself and others.
Family matters and so does what you do with your life. Remember, life is a marathon, not a sprint. There are no prizes for getting to the end first. Look after yourself and make the best decision you can. Best of luck
The example given is just one of many who might have little choice. Many others will just accept the new practices.
Once this is normalized and widespread, it gets increasingly harder to opt out.