For us you could work part-time, freelance, take a job share. You could do annualised hours, min-max hours, have a zero-hours contract (I know those contracts are very unpopular now but they did work well for us in those early days).
The only golden rule I follow, never expect another human to work as hard as me for something that mostly benefits me. I do not believe in shaming employees that only put in their 40 and get out. That's great, they care about different things in life. Some of them have hobbies, families, responsibilities, etc, and I respect that. But for the rest of us who have chosen personal business success as our long term goal and aren't particularly intelligent, we should not feel guilty for our 80 hour weeks. Sometimes it is just plain necessary. Stupid if it doesn't work out. But necessary if it is to work out.
In the mean time: how do you stay motivated to work the long hours? How do you maintain mental focus for extended durations?