As a relatively new father and founder, I wanted to share some thoughts about balancing both. It's definitely not an easy task, but it is doable (and worth the effort).
Some thoughts about how to do both:
1. Be Intentional
You're not going to happen onto being a great father and entrepreneur, it's takes dedication, planning, and practice. The first step is simply making both a priority.
2. Quality not Quantity
A common mistake that most of of us make from time to time is trying to be all things to all people at all times. This means being "on call" to check/reply to emails even when we're playing with our kids, or frequently going out of our way during working hours to be available to our families. It turns out, by trying to focus on many things at once, we neglect all things. When you're with your family, be with your family, and when you need to focus on the business, separate yourself from the family. Your family & your business partners will be much happier with shorter, but undivided, attention from you than twice as much "face time" without focus. Obviously the total amount of time you spend on both is always going to be a balancing act, but it does get easier with focused time.
3. Pick the Right Partners
I'm very proud to say that I believe all my Differential co-workers (who have families) are also doing a great job at this balance, overall. The reason I'm proud of this is because 1) without ever saying it, we send a message to each other that family is important and 2) we're modeling a good example for our younger employees who don't yet have families.
Don't get me wrong, we work very hard, but more nights than not we're home in time for quality time with our families. For me, this usually means something like getting home by about 6:30 so that I can spend some time with Nolan (including putting him to bed many nights) and eat with Kristy. Normally by about 8 or 8:30 I'm back to work, often till 12am or later.
4. Be Open to Feedback & Continuous Improvement
If you're currently part of a healthy relationship of any kind, you already know that open, honest and ongoing conversation is a big part of making that work. We're all flawed, subject to getting in a rut, affected by factors outside of our control. Because of that, it's important to be open to honest (read: sometimes painful to hear) feedback from our spouse, kids, partners, co-workers and friends, and then regularly take time to re-evaluate what's working and what's getting neglected.
I definitely have plenty of room for improvement, but I'm driven to be great at both and I welcome the continued support of my family, friends and co-workers!