Initially, Schwarzenegger recalls being a little taken aback when he learned that Katherine was dating Pratt, and even a little concerned that he might end up being usurped as the leading man of the family.
"I was, like, blown away when my daughter was telling me that she was going out with him," he said. "Because, I say to myself, 'You have to be so competitive? Do you have to have a guy that's taller than me? That is bigger than me? That is doing bigger movies than me? And all this kind of stuff. That makes more money than me? What is going on here?' So I think it was wild, to all of a sudden have this guy in the family... Of course, the first thing when we met, he says, 'Can we ever work out together? I need to have the inside scoop to pumping iron,'... So I took him to the gym and we worked out."
Schwarzenegger is a harsh critic when it comes to other people's gym technique, and is quick to correct people on their form — but he recalled being impressed by Pratt's performance, and can pinpoint the moment when he officially won his respect and a welcome into the family.
"Pumping iron was the decision-making factor," he said. "He's a strong guy, there's no two ways about it. I'm very proud of him... When I watched him make these moves in the gym, you know, the incline press specifically did it. Why I wanted him to become my son-in-law, it was the incline press."
Of course, there's more to being a good husband than brute strength, and Schwarzenegger also praised Pratt for his other qualities: "I'm really happy that he is such a great guy, not only a very talented guy and a great actor and a great star and all this stuff, but a really kind man, and kind to my daughter, which is the most important thing for me."
This article originally appeared on Men's Health