I recently became a father. By recently... I mean a year ago two days from now. All I can say is being a dad changes things (well, everything really) - in a good way. Yes, it ruins any schedule you thought you had (or would have). It also really impacts your sleep (and, admittedly, our son sleeps really well). It can necessitate a change in your priorities. It gives you things to worry about that make previous worries seem downright foolish. It can put stress on your marriage. These are just a few of the many ways having a child impacts your life.
But here's the thing, having a child also brings more joy into your life than I can explain. I've been up rocking my son at 2 or 3 in the morning and as he slowly falls asleep in my arms, he'll start laughing in his sleep. No matter how much I want to be upset or frustrated that I'm not sleeping, in that moment, it is almost impossible. Seeing him smile and laugh when my wife enters the room pretty much wrecks me every time. It also brings a level of focus to my life. I am a very motivated and self-driven person to begin with, but now I have even more reason to strive toward excellence. Not only do I want to be able to care for and provide for my family, I also want to set an example for how to live and work. I want my son to have positive role models at home. My personal growth and gain has expanded into something more; a desire to do my best work because one day he's going to ask me where I go every day, what I do, and why I do it. I want to not just say words to him... I want him to see my example every day.
I won't sugarcoat it, finishing my PhD and starting a career would have been a lot easier if I didn't have a child. That being said, I wouldn't trade my current situation for the world.