My start-up is also not a grind. My wife and I are the founders, and we put in our hours early on, but now we work a very regular 9-5 schedule. At least one of us has to leave around 5:15 to pick up our son.
Our employees are also not asked to work crazy hours - we don't rush to get releases out, we're profitable and growing, and we're not concerned about flipping the company tomorrow. Our employees are also now in their late 20s, and we expect them to have children and normal lives too, and we want them to stick with us through that.