The 36-year-old actor – who has 23-month-old Hazel with wife Emily Blunt – admits he had to refocus his priorities when faced with the responsibility of having a child and is now focused on ”becoming a better person every single day.”
He added: ”I went through some really serious stuff. There is a mirror that is held up to me now. You have someone watching you. You have to lead by example.”
And becoming a parent has taught John a lot about the people around him.
He told People magazine: ”I got to understand my parents better. I got to understand my wife better. I got to understand how lucky I am to be in the fox hole with someone I can rely on 150 percent.”
John also credits Hazel for making him a better actor and director when he began working on The Hollars, in which he plays a father-to-be whose mother falls ill.
He said: ”I had my daughter in February and then we shot the movie that April. Those four months changed my life. They are the reason the movie is what it is.”