1) I can actually get a lot more done in a 1 hour lunch break at work than a 2 hour session at night. Other people prefer to work in the mornings before work or even work a full weekend day. There's no reason why it has to be in the evening.
2) I'm lucky enough to have a high paying job, enough so that I can afford to have house cleaners, and I also pay my brother to do our laundry every few weeks (this is a win-win, since he gets spending money). Sometimes I feel bad for not doing these things myself, BUT in reality it's working and that's what counts. To be honest, if I made less, I might consider going for funding instead of working, but since I make good money, I consider that to be my investment in my business. That being said, I still have household chores to do, but you just have to get realistic about how much you can really do, whether that means getting help, or just NOT doing chores (sad, but true)
3) Since I know have much more limited time than other people, I really really REALLY need to find ways to keep the product lean and focused. Everyone says they try to do this, but you know, necessity is the mother of invention.
4) Finally, sometimes I'll be in bed, it's midnight and I need to wake up early for work. I'll start thinking about the product and get so excited I have to get up and work on it for an hour or so. And of course, since I'm pumped, I'm much more productive. This is horrible for my sleep, but I think it's a fair trade for starting a startup, in addition to living a full life with family and work.
5) Assuming you have a supportive spouse, he can take the kids for an outing to the zoo, or whatever, on Saturday mornings and you can get a good 6 hours in. We find it to be a win-win, since they get to spend quality time then.