Outlander: David Berry's mother-in-law convinced him to play John Grey 

Sunday night as Lord John Grey — was apparently not so keen on taking the high-profile role on the Starz drama until his mother-in-law convinced him to do it.

that his wife Kristina was preparing to have their first child so his instincts were to say no to executive producer Ronald D. Moore.

“What really sealed it for me to make the decision is my mother-in-law,” Berry told

. “She was like ‘just do it’ and [I think] that’s because she’s a huge superfan of

But that blessing made it more comfortable for both of us to think I could go.”

Berry had something particularly funny to say about playing opposite his handsome costar, Sam Heughan (Jamie Fraser). (Jamie meets Grey after he is thrown into Ardsmuir prison.)

“He works 12-hour days and then he goes to the gym,” Berry told the publication. “Sam in particular is that guy you can never compete with. He’s so perfect and it makes you feel inadequate. So I feel sorry for all those husbands and boyfriends out there because we will never match up.”

For more about Berry’s role in the new episode, make sure to check EW.com after it airs at 8 p.m. ET on Starz.

1 How to watch \'Star Trek: Discovery\' (and why it will cost you)

2 Trump claims NFL protest attacks not about race

3 \'Outlander\' actor, producer reflect on that shocking death

4 \'Teen Wolf\' boss on the series finale and who almost died

5 \'Star Trek: Discovery\' producer explains those first two episodes