The Turbo star, who is expecting his first child with wife Blake Lively, told People Saturday at The Michael J. Fox Foundation for Parkinson's Research Benefit in New York, "I don't have a weak stomach. I'm good with diapers and diarrhea and all that kind of stuff because I have lots of nieces and nephews, so I've done it all before."
As far as what he's looking forward to the most, the actor said, "I'm just excited about having a buddy. We don't know if it's a boy or a girl yet, but whatever it is, you have this tether to reality that never goes away."
While Ryan is excited about becoming a dad, he's also making sure not to spend too much time worrying about the small stuff when it comes to raising a child.
"For a lot of new dads, you tend to dwell on the mistakes you don't want to make," he continued. "I'm at that stage still where I'm focused primarily on being open and understanding and leaving a lot of room for error."
Before Blake announced her pregnancy last month, the 38-year-old actor wasn't shy about discussing his desire to have a big family with Blake one day, telling Details last August, "We'd love to have a big family. We both come from big families - my parents did four, Blake's did five. A lot of people say it's crazy, but we'll only know when we're there, you know? We'll walk through that fire pretty happily, I think."
According to E! News, it shouldn't come as much of a surprise if Blake is sporting a baby bump again soon after she gives birth.
"Ryan and Blake are in full-on baby mode right now," a source told E! News in October. "They are so excited they are having a baby and are happy Blake's had a pretty easy pregnancy. It's been so easy that she's saying she wants to get pregnant really soon after she pops this baby out!"