Diapers are easy. The tough part about being a parent, if you're going to be a good one, which I assume you will be, is that life as you know it is over. And that's okay. Going out, having fun, movies and dinner dates with your wife, just having the overall freedom to do whatever, whenever, is over. That baby is now in charge and he/she will dictate your life 24/7 and that won't really change much until they're out of diapers, old enough to dress themselves, make a bowl of cereal, little things like that will feel like amazing wins as a parent. It's a process, a wonderful journey I wouldn't trade for ANYTHING.
You'll soon realize that you love that baby/toddler/child more than anything you've ever loved by a wide margin. And that comes with incredible responsibility and changes to your thinking. For example; you'll begin to have irrational fears (or at least I do), which really caught me off guard, I never had those thoughts before kids. You'll just randomly have these fearful thoughts about something bad happening to your child and it terrifies you! And this isn't to scare you at all, it's awesome being a dad, but just know that if you're a good parent NOTHING matters more to you than your children. A hug from my 6 year old can be the best thing that happens to me all day. Playing basketball with my 9yo and blocking his shots to teach him about hard work, is awesome. All these little things that you won't realize until they actually happen to you, mean more than any movie, date, concert, or vacation you missed out on.
And then when they start to get older you realize (like I am these days) that, "Oh ****, these kids are going to be adults in the blink of an eye!" And that makes me sad because they're wonderful and amazing and soon will likely hate me at times as a teen and young adult lol. Right now I'm the king of the world, and that's a great place to be. The days are long but the years are short, my friend. Enjoy it, be great at it, and you'll be filled with an unimaginable amount of joy and happiness just from a smile or a hug.