One simple hack that can help you balance your work with your family is to take on the primary responsibility for picking up your kids from daycare/aftercare.
I’ve always picked up the kids before 6 PM, which forces me to leave the office.
Anyone who wants me to stay later, I simply tell them, “I get charged $4/minute for every minute I’m late.”
Erecting a hard, consistent boundary trains the other people in your company to respect your schedule.
This post started as a comment on Steve Blank’s post, “Epitaph for an Entrepreneur” which is well worth reading.