I'm dad to 6 children. I have 3 daughters from my first marriage - ages 24 (grad student), 23 (married RN who made me a grandfather in December), and 19 (college sophomore). I have an 18-year-old stepdaughter who just left for her first year of college yesterday, a 13-year-old stepson who is profoundly disabled (acro-colossal syndrome & autistic), and a 5-year-old daughter who starts kindergarten next week. Being a dad is expensive, time-consuming, and a seriously tough job that takes over your life and leaves you with very little time for yourself. It's also the greatest thing in the world.
Sad story, but a valuable lesson: One of my closest and oldest friends and his wife had their first child a few weeks before my first wife and I had our first child. When his daughter was a few months old she was diagnosed with a rare and fatal genetic disorder and passed away shortly after her first birthday.
It had a huge effect on me as a dad. Every time over the years that my kids would break something, poke holes in the new sofa, put peanut butter in the VCR, cut their hair, pour grape Kool-Aid in the carpet, rub lotion on my Strat, pour a gallon of milk on the dog, overflow the tub, dump a dozen eggs in the floor, take off their dirty diapers and finger paint the room with its contents, drop my cell phone in the sink or destroy the new phone I'd just bought them the week before, ding the car up, get a ticket, or any of the other countless things kids do (and mine did ALL of the above), I'd take a deep breath and remind myself that my friend and his wife would give 20 years of their life for a few minutes of that with their late daughter. It made me a better and more patient dad.